Colonel Jack O'Neill is brought out of retirement to lead a new expedition back to Abydos, only to find an old friend, a new enemy and a far wider use of the Stargate.

The team, now designated SG-1 are planning their next foray through the gate as they try to map out the variety of sites available to them and locate their missing friends. O'Neill asks that Teal'c be allowed to join his team but Gen. Hammond thinks that will be unlikely given that he is the host for a Goa'uld. Unknown to anyone, however, is that O'Neill's close friend, Maj. Charles Kawalsky, leader of SG-2, has been infected by a Goa'uld, an immature version that has not yet taken complete control of the host. Kawalsky is having regular blackouts during which the Goa'uld is trying to return to the gate. An MRI reveals what is wrong but it's unlikely the creature that has fused itself to Kawalsky's spine can be surgically removed. Meanwhile, Col. Kennedy arrives to question Teal'c who has pledged his loyalty to his new world.

While exploring a world populated by Mongol descendants, Capt. Carter is abducted for a wife of a local warlord.

The Stargate base is put in deadly peril when it is contaminated with a dangerous infection which causes its victims to become mindlessly animalistic brutes.

The SG-1 team is sent after the SG-9 team that has failed to return. They find that SG-9's captain, having been treated like a god by planetary inhabitants, is drunk with power and is tyrannizing them. Can they overcome him?

When Jack is injured unintentionally by a crystal alien, the alien duplicates Jack's form and out of fear of retribution tries to heal Jack. He returns to Earth in place of Jack, while Jack is still unconscious on the planet, to find the one thing he feels will accomplish this; the one thing that cannot be found again. Meanwhile, the 'real' Jack has returned and is trying to convince SGC that he is who he says he is.

With the Stargate program in danger of being terminated, the team is under pressure to find technology. Visiting a planet where they believe there is a creature that possesses the secret of invisibility, they encounter Apophis and his guards. Both sides receiving mortal wounds, they are aided by the planet's inhabitants, the Nox, a gentle people with a very large secret.

On the planet Argos, Kynthia seduces Colonel O'Neill, which gives him an Argosian lifespan of only a 100 days. As he begins to age rapidly, will the SG-1 team succeed in finding a cure?

SG-1 goes to the planet Cimmeria in search of allies against the Goa'uld. Upon arrival, Jack and Teal'c are trapped in a labyrinth, where the only exit is through Thor's Hammer, a device to destroy Goa'uld, but preserve the host. Daniel Jackson must destroy the device that could someday have saved his wife in order to free his friends.

Daniel Jackson discovers that the Stargate was activated in 1945 and a young professor went through, never to return. Together with his still living fiancée, the SG1 team discover the now aged professor, naked and trapped in a decaying fortress, containing the secrets of an Ancient alliance. Will they be able to rescue him and escape to earth in time?

It is time for Teal'c's son Rya'c to have his Prim'ta. Can Teal'c stop his son from being implanted with a Goa'uld and becoming a slave to Apophis?

O'Neill, Carter and Teal'c return through the Stargate shell-shocked and distressed to announce that Daniel Jackson was killed. But Jackson was captured by the last survivor of an aquatic race, who planted false memories in the other members of SG1. Can the team remember and return to rescue Daniel?

The Goa'uld Hathor (one of the mothers of all Goa'uld), brainwashes the men of the SGC with pheromones, and nearly makes Jack a host to a larva conceived with Daniel. She flees after the unaffected women of Stargate Command retake the facility.

On an astronomical black hole observation mission, SG-1 finds a fatal bacterial mass-epidemic on a planet where the natives told then-incredulous Daniel months ago that the coming solar eclipse would bring disaster. They also take back to the Cheyenne Mountain Base a surviving, fairly healthy, orphaned young girl named Cassandra, and awakes Sam's maternal instinct. The Naquadah traces found in her blood turn out to have made her immune, but after she has a seizure they are diagnosed to constitute a huge bomb, somehow triggered by rescuing her; the whole thing must be planned as a 'Trojan Horse' by the Goa'uld. Sam takes the prospect of sacrificing Cassie personally and is prepared to take personal risks.

SG1 travel to a planet where Teal'c is recognised as once having been head Jaffa to Apophis. He is arrested for the murder of a villager and put on trial for his life. Then other Jaffa attack the village. Will SG1 be able to save Teal'c and prove that he has changed allegiance?

On their first visit to a new planet, SG-1 finds it subject to totally destructive volcanic activity and saves ten natives, the Tollan, a far more technologically advanced society. Their leader Omoc isn't grateful, nor interested in such a primitive race as the earthlings or any of the 'even more primitive' planets which are prepared to host them. Only one Tollan, Narim, shows an active interest in life on earth, especially in captain Samantha Carter and the cat Schrodinger she gives him, explaining his planet was destroyed after the Tollan supplied an unlimited energy source to a primitive neighboring planet which abused it for a cataclysmic weapon. Meanwhile, the White House authorized NID colonel Maybourne to take charge over the Tollan for military purposes, exactly Omoc's nightmare.

Following a Stargate technical defect, O'Neill and Carter are stranded next to a Stargate in a cave on an icy wasteland. O'Neill is severely wounded and both are freezing. Will the SGC find and rescue them in time?

After arriving on P3X-989, the team are rendered unconscious. When they wake, they return to Earth, but soon find out that they are androids. The team must return to the planet to find out what happened to their real bodies.

While collecting artifacts on a distant planet, Daniel Jackson is knocked out after touching a mirror-like object. He awakens in the same room but is unable to locate the other members of SG-1. Assuming that they left without him, he dials up his return home but gets there to find that he is in a different reality. In this world, General Jack O'Neill and Catherine Langford are in charge of the Stargate program; Hammond is a Colonel reporting to O'Neill; and Sam Carter is a civilian scientist working on the project (and also engaged to O'Neill). More importantly, Earth is under attack from the Goa'uld who have already killed over 1 billion people. Carter believes that somehow, Jackson is from a parallel dimension. When Jackson learns the point of origin of the Goa'uld attack, he wants to return to his own universe, believing that his Earth will be similarly attacked.

The Stargate team must justify the project's continuation when a doubtful senator, Head of the Congressional Military Appropriations Committee, comes to review the project's performance.

General Hammond has tried everything to get the Senate's decision to shut down his Stargate program undone, but the President personally refuses to 'commit political suicide': the Stargate will be buried. Daniel's insistence -that the danger for Earth as a whole outweighs everything- convinces his colleagues to ignore Hammond's command and dial the address that the Goa'uld invasion started from in the alternate reality that he visited. They arrive not on a planet but a new, superior type of starship, already launched by hyper-drive. A 'video' proves it belongs to Apophis, who gives command to his son Klorel, whose host is none other than the team's young Abydonian friend, Skaara. Overpowering Skaara seems their best move, while Sam installs explosives in the death glider deck with a 24-hour timer just in case, but the Jaffa manage to liberate Klorel. Jack discovers that the ship goes far faster than expected.

As the Goa'uld attack fleet approaches Earth, all four members of the SG-1 team are taken prisoner. They get help from an unexpected source when Bra'tac, Teal'c's mentor, reveals that he is on board. Apophis has delayed the attack until his son Klorel is revived, giving them some time to prepare. SG-1 has used all of the C4 on one of the two ships but must find a way to dispose of the second. Back at Stargate Command, Lt. Col. Bert Samuels arrives as a Pentagon liaison officer but also reveals a new weapon they have developed. General Hammond is dubious. They begin to transport humans to an Alpha site in order to ensure the continuation of mankind.

Samantha Carter becomes the host of a Goa'uld when she was trying to save the life of the previous host.

SG-1 inadvertently help a desperate criminal and are charged and sentenced as accessories to his crime. They are banished to a desolate, brutal penal colony and strike a deal with a powerful female prisoner to help them escape. But is this prisoner hiding something from them?

Exploring a strange and beautiful garden, SG-1 comes across a dome containing a race that are connected to machines. The team are captured by the machines and rendered unconscious, but awake to find themselves reliving pivotal moments of their lives, over and over again. Then they discover it is virtual reality and a mysterious keeper appears to persuade them to try different outcomes for the moments. But can the team escape his clutches, when they don't know what is real and what is not?

While walking through a forest on another planet, Jackson saves the life of a beautiful princess who is about to kill herself. SG1 is taken prisoner, but Daniel is freed by the ruler when he finds out that he saved his daughter. The rest of SG1 is sent to work in the mines for the rest of their lives. Jackson falls in love with the princess, but also becomes intoxicated by frequent use of a Sarcophagus. Will he come to his senses before the rest of SG1 are worked to death?

O'Neill and the team return to Cimmeria, the planet where they destroyed Thor's Hammer to help Teal'c escape. They find that the Goa'uld have invaded and many of the people are dead. Can they help to find Thor's weapons to fight off the invasion before they are all captured or killed?

SG-1 discovers an ancient artifact and brings it back to the SGC. Ariving at the SGC, it becomes active, pins O'Neill to the gate room wall, and unleashes a virus into him.

Teal'c's son Rya'c is kidnapped by Apophis and SG1 tries to rescue him. When Rya'c is recovered he denounces his father and helps to capture the team. They escape, but will they be able to return to Earth and cure Rya'c?

While O'Neill and Carter head to Washington to be decorated by the President and find a security leak, Jackson and Teal'c go to Abydos (after they unbury their stargate) to see Sha're's father. They arrive to tell him that they have been unsuccessful in finding Sha're, only to discover that she is already on Abydos. But they find that she is pregnant by Apophis and the baby holds the secrets of the Goa'uld.

While exploring a new planet, Teal'c is stung by a giant insect whose venom causes a terrifying transformation.

When Teal'c makes Sam Carter realize how valuable the knowledge left by Tok'ra Jolinar in her brain and the chance for an alliance can be, they convince General Hammond to let SG-1 attempt a meeting. They arrive on a planet which is deserted on the surface, but are awaited by well-camouflaged, armed Tok'ra who bring them to tunnels which they create by means of a mysterious crystal, which can also undo them afterward. Both parties are quite suspicious, the team feels like captives, and indeed, the Tok'ra leader Yosuuf fears they cannot be released, at least until the whole site is moved. Meanwhile, the Tau'ri barely overcome their suspicion against the Tok'ra Goa'uld biology (with symbiote), when asked to volunteer themselves as 'hosts', and Carter learns Martouf (and his symbiote, Lantash) was Jolinar's lover, hence has a special connection with her.

The attempt to forge an alliance with the Tok'ra seems a miserable failure, as SG-1 is practically imprisoned as a security risk and considered virtually hostile because 'blending', by agreeing to host a symbiote, is a bridge too far for each of them. When SG-3 arrives and informs Sam about her terminally ill father General Jacob Carter's quickly worsening condition, she realizes the symbiote's healing powers, confirmed to apply to cancer, make hosting an offer to good to refuse for him. Garshaw allows Sam and Jack to return and convince both generals to allow the plan, which is achieved. Meanwhile, the Tok'ra must hastily evacuate, destroying tunnels behind them, because a large-scale attack by Apophis's troops is expected soon, while Jacob meets his potential symbiotic partner Selmak and his equally terminal predecessor to help him decide. Jack verifies his strong suspicion there is traitor among the Tok'ra who is communicating with the Goa'uld.

SG-11 failed to report regularly while mining trinium, a vital mineral for earth's defense against the Goa'uld. SG-1 finds them missing, and all traces cease at the site of arrow-heads made from trinium. Then they are all sedated by such arrows and brought to the village of Tonané, whose earthly tribal ancestry Daniel identifies by its animal totems. However, they are soon awake and released, their guns even returned, and promised to get their friends back, too, from the wolf spirit T'akaya, and the raven-shaped supreme spirit Xe'ls. The council of elders refuses to allow resuming of the mining, which is disrespectful to nature, but Tonané is delegated to be shown alternatives on earth. Both teams return to SGC, or so it appears; in fact, SG-11 is a series of incarnated spirits, who are soon convinced the earthlings are most untrustworthy.

A climate control device is stolen from a planet and SG-1 is accused of the theft. They have to find it and restore it before the planet freezes. Then weather on Earth starts to unexpectedly change and the team believe that the device has been stolen by rogue NID agents. Will they find it in time and how did the NID travel off world?

SG-1 travels to a planet whose people are allies of the Asgard.

Stargate Command opens a wormhole to a planet with a black hole in orbit.

Daniel falls victim to an invention that swaps his body with that of a dying man.

Following on a Tok'ra tip, SG-1 goes to a planet where they find the hated Apophis, nearly dying and under attack by death-gliders. They get back with him, realizing he was tortured by a rival system-lord with lasting harm. Apophis demands sanctuary, provided Dr. Fraiser can save his life, at least on account of the human host, but without a sarcophagus the prognosis for his symbiont is lousy; he offers all his Goa'uld knowledge in exchange for a new host, i.e. his life, revealing he was defeated by the terrible Sokar, once supreme system lord till an alliance lead by Ra and Apophis unseated him. The confrontation with Daniel, on account of Amaunet/Sha're and their son Klorel, and with former prime Teal'c, is bitter for all three. The Tok'ra send Martouf to warn the Tau'ri must hand over Apophis, but their warning is ignored- until Sokar proves he can bombard the iris with accelerated particles and ultimately cut through it, so the White House orders his extradition, but before they can he dies, unlike his host, an Ancient Egyptian temple scribe of Amun.

While testing new technology, a UAV malfunctions and crashes on a planet. SG-1 goes to determine the cause of the malfunction, but discovers that their presence may be causing serious injury to the planet's primitive inhabitants.

When an incoming wormhole is established at the SGC, the iris is over-ridden and opened. A young boy appears and tells the SGC that they are in terrible danger from a group of terrorists. But these terrorists are invisible creatures and they are determined to wipe out all humans to prevent them being used as hosts to the Goa'uld.

A solar flare sends SG-1 back in time thirty years to 1969. Captured by military police at Cheyenne Mountain, they escape with the help of a young Hammond and then must find the Stargate so they can return to the present.

Colonel O'Neill awakens and is told by new staff everything in the SGC is different because he was just revived after 79 years of cryogenic hibernation, as sole survivor of a disastrous SG-1 mission on a Goa'uld-ruled planet. He accepts to undergo a 'high tech hypnosis' to retrieve information of use in the present war against them, which is going badly, involving earth's ten endangered colonies on other planets. However Major General Trofsky, the new base commander, and his female assistant tell Daniel and Sam, in different sections, that each of them is the sole survivor: it's all make-believe to probe their brains about the weaknesses of earth and the Alliance of the four races. Meanwhile, Teal'c awakes on earth, where it took Dr. Frasier months to save him from death; there was no trace of his teammates, and he resigns when General Hammond refuses permission to keep searching. O'Neill hears Goa'uld language, gets himself free and discovers he's on a fake SGC, frees Sam and Daniel, only to be stopped by the female Goa'uld system-lord Hathor, who employs both Horus and Serpent Jaffa and demands the humans' help against her rival system-lords.

O'Neill, Carter and Jackson are trapped on Hathor's planet. Teal'c and Hammond go to Chulak to forge a rescue plan and recover the team.

Sam's father hopes that SG-1 can help find and neutralize Seth, an Ancient Goa'uld who the Tok'Ra believe may still be hiding on Earth after thousands of years.

The Asgard and three Goa'uld System Lords meet at Stargate Command to negotiate a treaty modification, but subterfuge and treachery threaten not only the success of the negotiations, but Earth itself.

When the SG-1 team discover a sealed chamber of nine dead Goa'uld, Daniel Jackson is exposed to the parasites that killed them and threaten to drive him insane.

While employing the help of a planet's highly intelligent children for a project, the team discovers their horrific imposed fate when they reach a certain age.

Alternate reality versions of Kawalsky and Carter are caught at Area 51 after coming through the quantum mirror.

A bounty hunter, tracking down a Goa'uld, captures SG-1 and informs them that they too have a price on their heads.

SG-1 arrives on a planet where a culturally 'medieval Catholic' community lives in fear of an Unas they believe to be a demon, which regularly collects human sacrifices to Satan - in fact hosts for System Lord Sokar's army. When Simon implores SG-1 to spare his beloved Mary and take him instead, they even nurse her chicken pox. Simon hopes they are sent by God to deliver them from the satanic burden, but the canon who rules the village as 'spiritual' leader is faithful to Sokar and fears his authority, which rests on his right to select the 'damned soul' to be sacrificed, has been challenged, so he declares Teal'c a demon and incarcerates all SG-1. Witch-trial-type ordeals see the Jaffa 'proven' a demon and executed by drowning, and Daniel refuses the canon's warning to leave immediately. When Teal'c's symbiote allows a resurrection even Sam hadn't expected, they are all designated possessed and sacrificed, along with Mary. Simon follows the Unas with a staff weapon to liberate them, but he's not alone.

SG-1 come across another SG team being attacked by Jaffa. They offer to help but are shot by the SG team members. When they awake, they find out that the other SG team are Jaffa, loyal to Apophis, who are planning to infiltrate Earth. Can SG-1 convince them that Apophis is dead before the Jaffa fight to the death?

Responding to a help cry from Kasuf, SG-1 and more USAF wipe out a Goa'uld Jaffa guard to save most of the slaves on Abydonia. When Amaunet turns her hand device on Daniel, he can't bring himself to shoot his beloved wife Sha're, but Teal'c saves him by fatally staff-shooting her, and Abydononian funeral tradition squashes his hope of a sarcophagus resurrection. Crushed by grief, Daniel has apparitions of Sha're and, once released from hospital, resigns from SGC claiming the quest for his wife was his reason to join. Daniel's former research assistant, Dr. Robert Rothman, succeeds him in SG-1; but Jack is sure he'll be back. Sha're (or Amaunet's posthumous manual spell?) keeps appearing to Daniel life-like, telling him to forgive Teal'c and together find their boy who, as Harsisis, has all the Goa'uld knowledge in his genetic memory, which, to the Goa'uld, means he must be killed. Daniel agrees to return, but has a secret agenda, too.

The team discovers an early industrial world suffering from collective amnesia and has no elderly people.

Martouf leads a Tok'ra delegation with crushing news for Carter: her father Jacob/Selmak has been captured by Sokar and imprisoned on Netu, an Egyptian name for hell, on a moon of planet Delmal, where prisoners are sent to suffer eternal torture, and from where no one returns; only Jolinar has ever escaped. SG-1 mounts a rescue operation with Martouf, top-priority being any information Selmak can offer about Sokar's plan to subjugate the other system lords, an unprecedented threat for all humanoids in the galaxy. Teal'c must pilot a Goa'uld ship and keep it in orbit as landing is impossible except by small pod, but first Martouf taps into Jolinar's memory, which is partially blocked by some trauma beyond physical torture. Only when they're down and in the custody of Netu's lord Bynarr, does Sam realize he is the key, in a 'personal' way, but not voluntarily, as she had thought. Sokar learns of their presence from Bynarr and orders the team and craft destroyed, but this also means there must be a way out. Bynarr's prime, Na'onak, has, and is himself, a major surprise.

Now that Apophis has revealed himself, he promises the prisoners to overturn Sokar, which requires extracting an irresistibly valuable secret, to which end he drugs Sam with the truth serum 'blood of Sokar.' Apophis also implants a memory device in, and gives the drug to, Jack to torture him using the persona of his young son that died, and Daniel for the location of his Harsesis son. Martouf's love for Jolinar makes him betray that the Tok'ra are on planet Entac - a convincing lie, so Apophis's plan to earn Sokar's gratitude, and then kill him when rewarded with the lordship of Netu, is on a shaky basis. Teal'c must help the Tok'ra Aldwin prepare a nuclear weapon to explode the whole moon when his ship arrives as their last chance to eliminate Sokar, but he decides to rescue SG-1 instead, by flying in the path of the rings device on Sokar's ship when he arrives.

An alien incursion takes control of the base.

The SG-1 team is requested by the Tollan to participate in a trial concerning Skaara and whether he or the Goa'uld parasite, Klorel, has control of his body.

The SG1 team embark on a trip to visit a planet with an idyllic beach, but as soon as they step through the stargate, they find they are back in the SGC. They thought that they just left, but have been missing for hours. They soon discover that an alien device has been implanted in their brains and a being called Urgo reveals himself to the team. But no one else can see him and he is extremely irritating. Will they be able to extract him before they lose their minds?

After a cataclysmic meteorite bombardment, Col. Jack O'Neill finds himself stranded on a primitive planet with its Stargate apparently permanently inaccessible.

Col. O'Neill is dismissed from the SGC for stealing alien technology, and is subsequently approached to participate in an even more covert Stargate operation.

While redialing old Stargate addresses, the SGC discovers that a gate that was previously buried has become uncovered. They send a probe through and find two archaeologists. However, when they travel through the Stargate, they find that it is located in a society in civil war: one continent believes that the people were created by a Goa'uld, whilst their enemy believes that humans arrived from another planet - by the Stargate. O'Neill, Carter and Jackson are captured by the authorities and questioned, but Teal'c is wounded and blinded. Can he help SG-1 escape the hostiles and get back through the Stargate?

SG-1 believes they have finally found Kheb, a planet with a temple where they believe the child of Apophis and Sha're, a Harcesis with all the knowledge of the Goa'uld, is being held.

The SGC send a MALP to a huge pyramid and inside they discover a crystal skull like the one Jackson's grandfather found many years before. SG1 visit the planet and whilst Daniel is looking into the eyes of the skull, as his grandfather did, an energy field envelops him. Teal'c fires his Zat at the skull, but Daniel has disappeared. Carter collapses and the team minus Daniel return to the SGC. Teal'c returns to collect the crystal skull, but will he be able to find Daniel?

Ready to go on vacation, O'Neill is beamed away by the Asgard. Thor tells him that Earth is faced with an enemy even worse than the Goa'uld.

SG-1 has to deal with a Replicator infestation on a Russian sub on Earth while Major Carter advises the Asgard about combating the menace in their galaxy.

The SGC is contacted by an advanced and embattled alien human civilization seeking military assistance, but their exact reasons for it become increasingly suspect.

The SGC is visited by a Tok'ra named Anise who brings some armbands used by the soldiers of a long extinct race, which are supposed to increase the abilities of the wearers. O'Neill, Carter and Jackson put the armbands on and it increases their physical strength, but it also causes them to make rash decisions. Can they get the armbands off before they cause their deaths?

An old love of Teal'c approaches the SGC and the Tok'ra claiming that her Goa'uld symbiote has been convinced to defect with their help.

When an SG-team member tries to assassinate the Tok'ra leader, it is believed that some of the SGC have been converted into Za'tarc - programmed assassins. The Tok'ra Freya comes to the SGC with Martouf to try and test all SG-team members. But the Za'tarc detector suggests that O'Neill and Carter are actually Za'tarcs. Is this correct and is there another Za'tarc at the SGC?

Col. O'Neill and Teal'c realize they and their friends are trapped in a time loop.

The SGC learn that the Russians have a Stargate of their own and they need the Americans' help with their problems with it that are affecting them both.

While on an archaeological dig at the original Goa'uld home world, Daniel is captured by a young Unas. He tries to communicate with it and slowly builds a rapport. Meanwhile, SG-1 comes to the planet to find Daniel and they soon realise that some of the SG-team members there may have been taken over by Goa'uld. Will they be able to discover which ones in time to rescue Daniel?

On the Enkarans' new home, SG-1 discovers a giant spaceship is threatening the colonists as it terraforms the planet.

The SG-1 team awake to find they have lost their memories. They believe they are workers in an underground power station. They are told that they are helping to preserve life during an ice age. In truth, they are slave labor to a huge domed city above. When Teal'c starts to recover his memory and is given another amnesia treatment, he forgets his Kelno'reem and starts to die. Will the others recover their memories in time to save him?

The SGC is contacted by a strange man called Martin, a conspiricist who believes he is an alien. The question is, how does Martin know about the Stargate and how come he has a gate address and is he being drugged by others?

While testing a new spacefighter made from Goa'uld parts, Col. O'Neill and Teal'c are trapped when a hidden automatic recall function takes over and sends it into space.

When one of Daniel's professors dies in a lab explosion which might be related to the Goa'uld, he comes back to Chicago to investigate what really happened.

Teal'c is on his home planet, Chulak, where there is rebellion among the Jaffa warriors. He is betrayed as a sacrilegious shol'va (traitor) by Rak'nor, son of a Jaffa friend of his father, and handed to Terok, the torturer of system lord Heru'ur. Ignorant of his fate, the other SG-1 members join Jacob in a risky attempt to take hold of a space mine using a Tok'ra ship piloted by Jacob. En route to Apophis' spaceship, the expedition finds out that Teal'c is being offered as a confidence-building present from Heru'ur to cement an alliance with Apophis against the other system lords, which would make the Goa'uld threat more dangerous than ever. They decide to save Teal'c, but their attempt fails. However, Teal'c's resistance to torture and clear conviction that Goa'uld are not gods finally convinces Rak'nor, who now bravely acts.

General Hammond mysteriously retires from the SGC and a new general is brought in, who breaks up SG-1: Daniel and Sam are scientists, Teal'c is with SG-3 and O'Neill commands a new SG-1. O'Neill tries to convince Gen. Hammond to return, but he finds out that someone ordered Hammond to leave or they would hurt his grandchildren. While the others are occupying the new general, O'Neill tries to find out who that "someone" is. Thereto he must place his trust in the one person he hates most: Maybourne.

In 2010, Robert Kinsey is president of a brave new world since he concluded the alliance with the Aschen, a race discovered by SG-1 which lets humanity enjoy its far advanced science and technology, including a vaccine against aging. Sam is now a civilian scientist, married to ambassador Joe Faxon, whose only worry is failing to get pregnant. When she double-checks the Aschen doctor Mollem's computer with Dr. Fraser, who felt superfluous given superior medicine, they discover human fertility is down 90% worldwide in three years. Sam, Daniel and Teal'c turn to retired general Jack, who always warned against handing over technological control, for a daring plan to turn the clock back like general Hammond did once, sending a message to their past with the exact time of a solar flare, which Sam can calculate using the Aschen computer. Only one ingredient is out of their reach: the GDO device to control the Stargate's iris, which is in the White House. Sam implores her husband Joe to steal it, but he has a secret as well as sincere objections.

When a "chosen" boy found on planet Abydos is brought to SGC, he sends a telepathic message, causing Daniel Jackson's personality to undergo disturbing changes. Will the rest of SG-1 be able to solve the mystery of the boy's origin before he becomes a power-hungry warmonger?

SG-5's Lieutenant Barber commits suicide by jumping into the Stargate shortly after a mission on a planet where a palace abandoned by the Goa'uld about 200 years ago is being studied by Daniel. Soon after, Daniel develops violent mood swings and is committed to a hospital with a neurotransmitter brain condition, presumed fatal after all the other SG-5 members die. Meanwhile, SG-3 has visited the planet, finding only the light installation Daniel reported as particularly fascinating and a human teenage boy, Loran, who hid from Daniel's expedition, but now tells Jack he was left there by his parents, scientific researchers. Back in SGC, Jack also develops symptoms. Sam and Dr. Fraiser conclude that it must be some addiction linked to the light, so when Daniel is nearly terminal Jack, who might not have been exposed too long himself, must bring him back. Jack insists they try turning off the light, and leans on Loran, who is looking for a father-figure; he even gives Teal'c an early "birthday present," but has a dark secret.

Carter decides to inspire a brilliant but difficult Air Force cadet by introducing her to the SGC program.

When the SGC probes a new planet, an alien energy entity there responds by invading the SGC's computer systems, and then Major Carter herself.

On Juna, SG-1 gets a hostile welcome from the local warriors' leader Darian, who seems incredulous they even dared to return. They loyally deliver Sam and Teal'c to Cronus and told them to bury the Stargate. Cronus orders Darian to decapitate Daniel by staff weapon- to find his head is robotic. Cronus's obvious astonishment makes Darian doubt his divinity. At the SGC, Harlan urge them to go on a mission. The master robot-creator tells SG-1 that the robot versions of them he created need to recharge after 48 hours. In order to prevent the Goa'uld gaining access to their duplicates' memories, SG-1 reluctantly go to Juna. Darian now joins them, but feels most of his people won't dare challenge Cronus. The two Teal'cs concentrate on revenging the original's father by attacking Cronus recklessly, while the Sams and Jacks deal with the military problems and overthrowing the Goa'uld rule.

SG-1 delivers their newly confiscated Goa'uld mothership to help the Tok'ra evacuate their planet and deal with their disinformed Goa'uld spy in their midst.

Stranded in another galaxy while fleeing their attack on Apophis' fleet proves only the beginning of SG-1's problems as multiple enemies appear.

To help Teal'c's mind clear again, SG-1 asks Bra'tac to help. Bra'tac removes Teal'c's Goa'uld and Teal'c is forced to remember certain memories of his past in order to get back to the real Teal'c in the end. SG-1 is glad to have him back.

After being rendered unconscious during an expedition, Carter's subsequently-ordered furlough is interrupted by a mysterious being with a message and growing affection for her.

When SG-1 flees from an expedition with Col. O'Neill and some mysterious team member named Tyler, whom no one else knows about, stranded, the fitness of the team is questioned.

When SG-1 inadvertently dooms a planet upon arrival, the team must overcome Asgardian diplomacy and indigenous religious prejudice to put things right.

When Cassandra collapses at home, she is taken to the SGC for treatment. A retrovirus is causing her to emit an EM field and she expresses a need to return to her planet for an initiation ritual. SG-1 investigates and finds a Goa'uld laboratory, probably having belonged to Nirrti, meant for experimentation on the planet's population. They find that the ritual is part of the experiment, a time when Nirrti studies her subjects and cures them when she is done. SG-1 has found a way to cure Cassandra, but now all that remains to be found is Nirrti.

When Daniel's Unas friend, Chaka, is captured by another world's slavers, SG-1 goes to that world to rescue him.

SG-1 teams up with a Russian task force to investigate the disappearance of a Russian SG team on P2X-338. They discover that the Russian SG team released a creature that killed Marduk, a Goa'uld, in his sarcophagus. SG-1 must trust their Russian partners in order to escape the ziggurat alive.

With the death of Omoc, the subsequent sudden Tollan reconsideration of their tech embargo leads to SG-1 suspecting a government conspiracy.

SG-1 makes contact with the Aschen, unaware of that their homeworld is one they were warned previously from the future to be considered off-limits.

Carter gets kidnapped and taken to an abandoned hospital where two doctors work to study the remains of Jolinar. She finds out that they have a Goa'uld, taken from the Russians, which they are planning to put inside a man named Adrian Conrad to heal his sickness. They need Carter to tell them how to get the Goa'uld out after he's healed. O'Neill believes the government is involved with Carter's disappearance and contacts Maybourne. Together, with Daniel and Teal'c, they find Carter but also find out that the Goa'uld has escaped inside Conrad's body.

A strange ship is headed towards Earth, and the SGC suspects that Martin Lloyd and his companions may have something to do with it. O'Neill is sent to speak to Martin and is assigned as a military consultant on Martin's new show, "Wormhole X-Treme!", which uncannily resembles SG-1 despite Martin once again losing his memory. His former shipmates stall Carter and Daniel by throwing them off the trail and into the hands of the NID.

While SG-1 is conducting training exercises for new recruits, Jack gets a call about a "foothold" situation. Wounded by compromised officers, O'Neill must lead the recruits in retaking the SGC.

When Teal'c is trapped in the Stargate buffer, the team must juggle the technical challenges along with personal, interdepartmental and diplomatic rivalries to rescue him in time.

In a Tok'ra plan to wipe out the Goa'uld, Daniel goes undercover as Yu's servant to release a poison at a meeting of the system lords. Meanwhile a Goa'uld attack on the Tok'ra base leaves the rest of SG-1 with their hands full.

As the Goa'uld summit continues, Daniel finds himself face to face with Osiris. He fools him in the same fashion as he did with Yu, but cannot bring himself to cause the death of Sarah, Osiris's host. He remains to uncover information about the unknown master of Osiris. Lantash, having taken Lt. Elliot as a host, guides the rest of SG-1 in escaping the fallen Tok'ra base.

A large asteroid is discovered on a collision course with Earth.

A new leader has risen among the Free Jaffa, K'tano, former First Prime of Imhotep. SG-1, accompanied by Bra'tac, seeks an alliance between the Tau'ri and the large force he has amassed.

On an alien planet, SG-1 discovers an inactive android is the only survivor of the destruction of her civilization. They bring her back to the SGC for study and manage to reactivate her. Things take a turn for the worse when she "makes" a replicator bug for Daniel.

To fix a mistake caused by the fake SG team, the real SG-1 must enlist the help of two convicts. The threat of an approaching Goa'uld mothership stresses the repair of the Sentinel.

As Jackson suffers from a fatal dose of radiation, he struggles with the value of his life while his friends deal with the emotional and diplomatic repercussions.

While still dealing with the loss of Daniel Jackson the SGC is contacted by the Asgard who require assistance dealing with Anubis, who seems to have new shield technology that can repel Asgard weapons.

When SGC detects an Goa'uld ship in orbit, SG-1 is dispatched with Jacob Carter to investigate. They find the ship to be abandoned with no discernible life signs and Sam determines it to be the same used to kidnap Thor. Once on board the Goa'uld vessel, they find that the crew had initiated a self destruct sequence. O'Neill would very much like to salvage the ship despite Jacob's warnings that it could be a Trojan horse. An examination of the computer core reveals that Thor may have been able to introduce a virus but Jacob was right: it's an ambush and the ship soon plunges in the ocean. SGC and the Navy mount a rescue operation.

O'Neill's symbiont Kanan drags him to a planet ruled by the Goa'uld Ba'al, where Kanan was undercover. Ba'al captures and tortures O'Neil, whose only hope may lie with - Daniel Jackson?!?

A television news crew has unearthed information about an Air Force project called "Prometheus". They believe it to be a generator, but know it uses Trinium, an element not found on Earth. In order to keep them quiet the Air Force allows them to film the X-303, a spaceship based on Asgard technologies, otherwise known as Prometheus. Things turn south when the news crew arm themselves and hold the Prometheus, as well as Sam and Jonas, hostage.

Having regained control of the X-303, the SG-1 team finds itself in an unknown part of space. Rescue comes in the form of the Asgard, specifically Thor, who needs their help. The Asgard home world has been overrun by the Replicators and they require SG-1's help as well as the relatively low tech X-303. The Asgard had set a trap for the Replicators and hoped to use a time dilation device that would give them the time they need to find a way to defeat them. The problem is that the Replicators have turned off the device and the Asgard want SG-1 to go in and activate it. They accept the assignment but to meet their objective, O'Neill will face a moral dilemma.

The US and Russia reveal Stargate Command and its operations to representatives of the other permanent members of the United Nations Security Council.

Teal'c is having strange nightmares featuring Apophis in which he is human and a firefighter with the rest of his team alongside him.

Riding in the elevator in the SGC, O'Neill is visited by Daniel Jackson who needs his help. Daniel tells him that Anubis is headed for Abydos to search for something called the Eye of Ra, a relic that would make Anubis all-powerful. It's essential that SG-1 go to Abydos and secure the Eye but no has seen it - including Daniel - nor has anyone ever been able to find it. On the planet they see their old friend Skaara and with Daniel's help locate the Eye. They also find a tablet that speaks of a lost city of the ancients. When Anubis and his troops land in force there is little anyone can do to stop them. In the end it's left to Daniel to decide if he will try to stop Anubis - thereby breaking a cardinal rule of the Ancients.

A group of nomads on an alien planet find Daniel Jackson naked in the middle of ruins and take him in. Jonas translates the tablet Daniel said was important and discovers that it describes the last city the Ancients were building before the plague. He surmises that the list of addresses Jack put into the computer while storing the Ancient data were Ancient outposts in temporal order. Thus the last of the addresses should be the "City of the Lost". SG-1 visits the planet and happens upon the nomadic people, now inhabiting the ruins of the Ancient city. There they find Daniel, but discover his memory is gone. They must recover his memories in order to discover the secret to defeating Anubis.

Anubis's super weapon has been put out of commission, but Yu's fleet has been diverted to the other side of the galaxy by Yu himself, allowing Anubis to escape into hyperspace. Jonas has been captured by Anubis and Daniel is still aboard Anubis's ship, evading capture. Anubis uses the mind probe on Jonas, learns of Naquadria, and begins his attack on Kelowna. The Kelownans seek aid from the SGC. Jack and Sam arrive on Langara to discover that the Kelownans have given Anubis Naquadria in order to secure their safety. They communicate with Daniel who is attempting to free Jonas. Teal'c has convinced Yu's first prime to seek a new leader of the System Lords, Ba'al.

A teenage boy shows up at the SGC claiming to be Jack O'Neill. He recalls a dream in which an Asgard was studying him. They determine that they must find this Asgard to fix what has been done to Jack.

In a firefight with Jaffa, Teal'c takes a staff blast to the gut. Without his symbiote, he cannot regenerate as he once did. Daniel feels that he cannot remember something important, so he goes searching through the logs for any sign of his lost knowledge. Teal'c expresses his feelings that the Tritonin has made him weak.

SG-1 investigate a seemingly idyllic and subtly advanced human colony sheltered inside an energy dome on an otherwise inhospitable planet.

While exploring a crashed alien ship full of passengers in cryostasis, an alien force has downloaded a number of their consciousnesses into Daniel.

When an SG geological exploration mission runs into deadly conflict with an indigenous Unas clan, Daniel gets Chaka to help seek an accord with it.

In exchange for new tech for the SGC, Warrick Finn asks for their help to win a dangerous spaceship competition.

To save his job, Dr. Felger tests a new virus on the Stargate Network to help control it and it ends up disabling it instead.

After being saved by a group of free female Jaffa, SG-1 is taken to the females' home world to meet their leader, Ishta. Ishta proposes an alliance between her all-female rebel group, Haktil, and the Tau'ri. The Tau'ri offer her Tretonin to supplant their practice of taking the symbiotes from defeated Jaffa in the service of the Goa'uld. However, since Tretonin has only had two test subjects, Teal'c and Bra'tac, they are cautious to spread it among their ranks.

Bra'tac and Teal'c encounter a heavily armed enemy with shielding protecting him from Goa'uld weaponry who took out two Goa'uld personal guards. They barely manage to defeat him and bring him back to SGC for study, but this new threat poses a greater problem for the Tau'ri.

The Tau'ri and Tok'ra have used their captured super-soldier to determine his planet of origin. With Daniel, Dr. Lee, and the Ancient device they found in the hands of Honduran kidnappers, SGC must find a way to retrieve them if they are to have any chance of defeating the newly encountered super-soldiers.

During an engine cool down break from hyperspace travel the crew of the Prometheus, with Major Carter as an advisor, encounter a space craft of unknown configuration. They hail the ship to no avail; the unknown craft opens fire upon the Prometheus. Carter attempts to override the safety protocols on the hyperdrive to make a short jump into a gas cloud, but in the attempt is knocked unconscious. She awakes to find the ship devoid of all its crew and, as she tries to escape the gas cloud by herself, she begins to hallucinate.

Jonas Quinn returns to the SGC to ask for assistance in saving his nation. He explains that the Naquadria was originally Naquadah and a Goa'uld named Thanos started a chain reaction to transform all of his planet's Naquadah into Naquadria. A large vein of Naquadah has just been affected and the Kelownan scientists believe that the transformation will cause this large a deposit to explode, taking their entire nation with it.

Maj. Carter has been set up with her brother Mark's friend, Pete Shanahan, a cop from Denver who thinks Carter works for the Air Force in a simple research capacity. Daniel Jackson is being visited in his dreams by his former lover, Sarah Gardner, who was possessed by the Goa'uld System Lord Osiris.

At the new Alpha site, Sam Carter and Selmak (the symbiote carried by Jacob Carter, her father) are working on a new weapon to defeat the Anubis superdrones when the planet is attacked by a fleet of Goa'uld ships. Carter escapes with the prototype weapon before the base auto-destruct is activated but finds herself being pursued by a superdrone.

The president has asked that a documentarian go to SGC to create a film about its operations. His arrival is unwelcome to most and he begins to clash with the base personnel. Nevertheless, he conducts his interviews with SG-1 and the scientists in the employ of SGC. Meanwhile, an off-world SG team finds the remains of an Ancient city.

The documentarian still a thorn in their side, SGC encounters an unforeseen predicament. With half of SG-13 off-world engaging enemy Jaffa, SG teams 1, 5, and 7 go in as backup. In the midst of heavy fire, O'Neill takes a staff blast to the chest. Many deaths from the encounter hit SGC hard and Senator Kinsey orders a full investigation into the matter.

Agent Barrett of the NID calls SG-1 to Los Angeles for a consult on a mass murdering of a rogue sleeper cell by a young woman. There they find many Goa'uld artifacts relating to Sekhmet, a subordinate of Ra. But how this operation is related to the Goa'uld eludes SG-1.

The newly inaugurated President of the United States is briefed by the Head of the Joint Chiefs of Staff on the Stargate program. Former Senator, now Vice President, Kinsey attempts to get his running mate to back his policies for the program, but the president decides to look into the situation himself. Kinsey gets Richard Woolsey to convince the president of his agenda.

Vice President Kinsey briefs Dr. Weir on the Stargate program before her meeting with the president. SG teams 1, 3, and 5 go off-world to attempt the extraction of a newly found Ancient repository device. Upon arriving at the location of the device, SG-1 comes under fire from Goa'uld ships. With no other way to disallow Anubis from claiming the knowledge for himself, Jack submits himself to the dangerous device.

With Jack having the knowledge of the Ancient repository once again in his mind, he and Daniel attempt to unearth the location of the Lost City of the Ancients. Bra'tac, bringing with him the news of an impending attack on the Tau'ri by Anubis, takes Teal'c to help him acquire ships and warriors for the defense of Earth. Dr. Weir attempts to cope with the overwhelming nature of her new job, while also dealing with the unrelenting ego of Vice President Kinsey.

In a last ditch effort, O'Neill activated an Ancient weapon in the Antarctic to defeat Anubis. With Jack still in stasis in the Ancient outpost buried in Antarctica, SG-1 tries to contact the Asgard. Meanwhile their new leader, Dr. Elizabeth Weir, tries to decide what to do about a request for peace talks from the Goa'uld System Lords.

The Asgard fleet has managed to destroy the Replicator ship, with Carter aboard, but cannot contain the debris. Talks break down with the System Lords, ending in a Ha'tak being dispatched to test Earth's new defensive capabilities. The Prometheus waits to engage the incoming enemy, but Thor arrives in the Daniel Jackson, with Teal'c aboard. They enlist the help of Daniel and Jack, still in stasis, to remove the threat of the replicators to the new Asgard homeworld.

General O'Neill is still in the early days of commanding the SGC and faces a major problem when newly arrived Russian Col. Alexi Vaselov collapses in his quarters. Dr. Brightman's belief that Vaselof may be contagious seems correct when Daniel, who was with the Russian when he collapsed, apparently goes mad and tries to leave the base through the gate. O'Neill locks down the SGC but the problem isn't contagion: the essence of Anubis is alive and well and seeking a new host.

As the new head of the SGC, General O'Neill is beginning to feel the weight of his load, and he starts to have second thoughts about the whole idea, questioning his own competency.

The discovery of the Stargate creates a war between two nations on the planet Tegalus with Daniel in the middle of it.

Dr. Lee is adapting a virtual reality chair for use as a training device. Teal'c thinks its current scenario is all too easy and agrees to work with them to make it more realistic. He enters the game scenario and is quickly "killed" at which point the chair shocks him. Lee says it must be part of its basic construct. As the scenario resets - it's an invasion of SGC by Goa'uld - Teal'c is repeatedly killed and shocked putting him in danger. The computer program is set up to learn after each scenario and the challenge for Teal'c increases at every turn. Daniel volunteers to enter the game as well to see if together they can find a way out.

Having obtained permission to live off the base, Teal'c rents an apartment, telling neighbors that he has recently arrived from Mozambique. He's under orders to keep a low profile but can't seem to help himself when it comes to helping his neighbors. He helps one who is about to be assaulted by three thugs, but it's his next-door neighbor who seems to need assistance. Krista is having problems with her boyfriend, Doug. Teal'c soon realizes that Doug is beating her and warns him that should he hurt her, Teal'c will kill him. It all becomes very difficult when Doug is found dead in Krista's apartment. Daniel Jackson soon after receives an offer - translate a Goa'uld text, and he will get ironclad evidence that Teal'c is innocent. Meanwhile, Carter is shocked when her boyfriend Pete Shanahan tells he asked for a transfer to the local police department and asks her to marry him.

Owner and CEO of Colson Industries declares in a press conference that there is alien life and that he has proof. SGC fails in its attempts to keep him quiet on the battle over the Antarctic. However, they are greatly surprised when the proof he shows the media are not his satellite images, but a living Asgard.

Teal'c is unhappy with his son's plans to marry. Ishta arrives bringing news that Hak'tyl may be compromised. Complications arise when O'Neill allows Hak'tyl to inhabit SGC until a new homeworld is found for them.

When the Stargate gets beamed out of SGC in the middle of the night, Teal'c is stranded off-world. Dr. Jackson and Colonel Carter attempt to recover the gate.

The replicator Carter and the real Carter work together with the disruptor signal. The replicator has a different plan.

General Hammond returns to SGC to take Dr. Jackson with him on a trip to Atlantis onboard the Prometheus. In the middle of their trip, the Prometheus picks up a distress signal and Hammond decides to investigate. Things get sticky when a Kull Warrior takes control of the Prometheus, leaving Hammond and his crew, minus Daniel Jackson, behind in a damaged Alkesh.

SG-1 is sent to warn Harry Maybourne that the goa'uld System Lord Ares is coming to the planet where he was banished, and in the process they find what may be an Ancient time machine.

Ex-Vice President Kinsey comes to Jack informing him of the Trust's activities including what seems to be a plan for the Russians to reclaim the Stargate they lent to the United States. He decides to use Kinsey as their inside man with the Trust. Kinsey wears a wire for his meeting with the Trust to set up a meeting with a high-ranking Russian general. The plan goes south when the signals get jammed just as the Trust makes an astounding revelation to Kinsey and they beam out.

A man breaks into Jack's house and hold him at gunpoint claiming that Jack ruined his life. Seven years ago he came upon an Ancient artifact at a garage sale that allows him to see all of SG-1's missions.

After a long absence, Jacob Carter returns to the SGC to tell Jack that the galaxy is under threat of takeover by the Replicators. The Goa'uld are under attack from the Replicators and are quickly being eliminated. Ba'al's armies are being destroyed and he arrives at SGC to suggest they work together to defeat their common enemy. Carter's doppelganger, RepliCarter, is leading the attack and she has kidnapped Daniel Jackson in the hope of learning of any weapons the Ancients may have created that could defeat them. Jackson gets help from an unexpected source - the Ancient, Oma Desala - or so he thinks.

Sam and Jacob are on the planet Dakara trying to configure the Ancient's device to destroy the Replicators once and for all, helped partly by Ba'al and Daniel, who succeeds in freezing the Replicators by manipulating Carter's duplicate.

Daniel finds himself in a strange time and place - a diner where Oma is working as a waitress. She gives him a clear choice - he can choose to die or to ascend but if it's the latter, he will not be able to help his friends fight Anubis, who has yet to be disposed of. He strikes up a conversation with another patron, Jim, who has his own take on the situation. Meanwhile, Sam decides the time has come for her fiancé to meet her father, Jacob. Jacob is not well, however, something he has kept from Sam for several weeks. After Pete surprises her - he thinks he's found the perfect house for them - Sam realizes she has to come to grips with her feelings for someone else. Teal'c and Master Bra'tac have information that Anubis may be gathering what remains of his forces for an attack on Dakara.

With the threats of both the Replicators and the Goa'uld greatly diminished and the sister ship to the Prometheus, the Daedalus, now under construction, SG-1 is anxious to get a ride on the new ship. However, the mood is somewhat darkened by a phone call informing Dr. Jackson of Catherine Langford's death. After the funeral, Catherine's niece gives Daniel "a few odds and ends" that her aunt wanted him to have. Upon delivery it is discovered that almost her entire collection was shipped to Daniel's lab. He finds in one of her books a possible location of a ZPM, but scans of the area showed that it was no longer there. Daniel proposes that they use the Ancient's time machine to take it from Ra at Giza in 3000 BC.

SG-1 has changed the course of history and made the SGC virtually non-existent. Doctors Carter and Jackson have helped Brigadier General Hammond to find the Antarctic Stargate, but are not being allowed to help any further. They help Jack to power up the time machine, and he gets Hammond to allow them on the mission to Chulak to find Teal'c.

With a new commander of the SGC comes a new leader of SG-1, Lt. Col. Cameron Mitchell, a former fighter pilot who flew an F-302 in the battle over Antarctica. However, he is deterred by the fact that all the other members of SG-1 are leaving for other ventures: Teal'c to manage the Jaffa Nation, Carter to Area 51 for alien R&D, and Dr. Jackson to Atlantis as an Ancient expert. Mitchell endeavors to keep the members of SG-1 for himself, but they are increasingly tough to convince.

Upon finding Merlin's testing grounds, Dr. Jackson, Teal'c, Col. Mitchell, and Vala uncover the hidden treasure including a book that tells the story of the Ancients coming to Earth from another galaxy and a strange alien device.

Daniel and Vala have used the Ancient device to inhabit the bodies of people in the Alterans' home galaxy. They have been taken by a Prior of the Ori to meet the Doci, one who speaks with the Ori, their gods. Daniel surmises that the Ori are what the Alterans who became the Ancients left behind and have ascended in a similar fashion, but without the restrictions.

Vala returns to the SGC upon having been separated from Daniel for a little under an hour. The effects of the bracelets have not diminished even though they have been removed. In order to get the effects reversed, Mitchell, Jackson, and Vala must deal with many people that Vala has used over the years to gain favors.

Vala leads SG-1 to a planet which the Priors have visited with a plan to keep them from worshiping the Ori. Once there she reveals that the symbiote that once held her ruled over this planet. She feels that keeping them in allegiance to her will hinder the spread of Origin to this world.

A Prior of the Ori has established an ever-growing forcefield on a Jaffa-controlled planet called Kalana. A minor Goa'uld named Nerus, who engineered the multiple Gate connections required for the defeat of the Replicators, comes to the SGC with information on the event and offers his help.

Following the death of a Jaffa on Earth and the disappearance of a prominent businessman, SG-1 starts an investigation into what remains of the Trust and into the actions of the Jaffa Nation. They discover that Ba'al is hiding on Earth after losing his forces to the Jaffa and that the Jaffa are secretly attempting his capture.

SG-1 investigates a planet that is said to be the home of the Warriors of Sodan, a legendary tribe of Jaffa said to have not served the Goa'uld in 5,000 years. In an encounter with the warriors, Mitchell deals a deadly blow to one of the Sodan and is captured and taken to their village. There he awaits a battle to the death as punishment for his crime.

SG-1 finds a Goa'uld-Human hybrid in stasis in an abandoned Goa'uld lab and take it back to Earth to study, where they learn it was created using Anubis' DNA.

The Ori unleash a deadly plague on Earth, prompting a powerful ally from SG-1's past to come to their aid.

The plague continues to spread among the US population and the President has quarantined the nation. Teal'c is pleading with the Jaffa High Council to reject Origin, but Gerak arrives, having been transformed by the Ori into a Prior. Cameron and Daniel seek the blood of the Prior that caused the plague in order to cure it, but have once again been captured by the Sodan.

On another planet, Mitchell is placed under arrest for the murder of a scientist.

SG-1 returns early from a mission only to realize that they and Gen. Landry aren't on the same page as far as the the mission they've just completed is concerned. The confusion is quickly resolved when the "real" SG-1 returns at the correct time. Dr. Lam examines them all and concludes that they are identical and thinks they might be clones. Sam however thinks they may have come from a parallel universe as the result of the black hole they created when they destroyed the Ori beachhead. As more SG-1 teams arrive from other alternate universes, one of them includes Dr. Fraiser and another includes the Tok'ra Martouf. It's left to Sam and Martouf to find a way to send them all home.

Leader of the Hak'tyl and their representative on the Jaffa High Council, Ka'lel has fallen in with those who work against a democratic Jaffa nation. Things worsen when she incapacitates and turns a well-spoken brother Jaffa who promoted democracy. Bra'tac comes to Hayes and SG-1 for help in finding a now missing Teal'c and uncovering the shadowy dealings in the Jaffa High Council. On Earth, Mitchell gets an old friend of his into a hospital where alien-based technology is used; hopefully, the advances they have made will be able to cure what ails him.

A contact within the Rand Protectorate comes to Earth with news that the Ori have given his people a superweapon to use against the Caledonian Federation in exchange for their conversion to Origin. SG-1 plans to turn the people from their newfound religion and destroy the superweapon.

While investigating the source of an addictive corn-like crop, SG-1 becomes involved in a firefight. They are forced to fall back to the gate, but as Daniel is dialing both the Stargate and the DHD are beamed away.

SG-1 is tasked to accompany members of the International Oversight Advisory, including Richard Woolsey, on a tour of the Gamma site. The visitors are suitably impressed but everyone is put in danger when a carnivorous insect escapes from the lab. The base is locked down and no one is allowed to travel through the gate. The bug is linked to the Ori - it's appeared on several planets that they've visited - and Daniel thinks it may be their follow-up to the virus. SG-1 and the IOA visitors take refuge in a cave, but Gen. Landrey is left with little choice but to flood the planet with a deadly neurotoxin to destroy the bugs. SG-1 looks for away out before that happens.

Sam manages to activate an Ancient device they found at the Glastonbury site and she and Mitchell are shifted into a phase that makes them invisible to everyone. Daniel soon figures out just what is going on but Dr. Lee's proposed solution sends Daniel to the same plane as Sam and Mitchell. There he is able to translate information explaining that Merlin had created a weapon against the Ori - and provides a gate address where it can be found. Meanwhile, Teal'c travels to a Jaffa planet that has sent out a distress call. The two events are related.

Using the Ancients' communication technology, Vala, who is in the Ori galaxy, contacts the SGC. She tells them that after being sucked into the wormhole she awoke in a bed in a village much like the one she and Daniel had visited when they used the communication stones. The locals think she fell from the sky - a gift from the gods - and befriends the gentle Tomin, a devout follower of the Ori who has a bad leg. Vala has two pieces of information for the SGC: first, she is pregnant though insists that she didn't have sex with anyone; and second, the Ori have been building a fleet of ships and building up its army. Meanwhile, Colonel Chekov advises General Landry that the Russians will not be renewing their working agreement with the United States and will be taking their Stargate.

Based on the information Vala gave them, SG-1 travels to the planet where Merlin may have hidden his secret weapon to defeat ascended beings. There they find an appropriately medieval village and learn that Merlin kept a library there. The locals have never been inside owing to a curse on anyone who dares enter, but SG-1 finds a way in. Once inside, they find a secret chamber that may reveal the location of the weapon. The SGC, meanwhile, has located the Ori's Supergate. Sam's attempt to get control of it is too late, and four Ori ships make their way through. In the ensuing battle, much of Earth's fleet is destroyed, and the future of several SGC members is left in doubt.

As the Ori invasion continues, Vala and Daniel must deal with their leader, Vala's young daughter, who is rapidly aged by the Ori to serve their purposes.

The team goes off-world and ends up in serious trouble. Meanwhile, Landry is faced with having to decide whether or not Vala can be trusted to remain at the SGC.

While Daniel and Vala search for Merlin's anti-Ori weapon in Atlantis' library, Mitchell, McKay and Carter try to to dial the Ori Supergate in the Milky Way.

The SGC is approached by an Al'kesh bomber which lets itself be taken down, so they can capture Ba'al, who offers to exchange the necessary information to find Merlin's weapon for human help to eliminate his clones, which want to kill him. They mistrust his story, as does NID Agent Malcolm Barrett, who, however, fails to take over the investigation. Since the captive might actually be a clone, several missions to different planets retrieve and capture all clones, but which is the real Ba'al, and what are his true intentions?

A mysterious creature targets members of Stargate Command one by one.

Martin Lloyd seeks out SG-1 for assistance when his failed TV show based on the real Stargate program becomes a feature film.

SG-1 is caught in the middle of a war after the Jaffa use a powerful weapon to kill 10,000 Ori followers.

Vala is kidnapped by agents of the Trust who are trying to find an ancient treasure when an accident causes Vala to forget who she is.

Cameron Mitchell must go undercover inside the Lucian Alliance to find the location of the hijacked Odyssey.

During their quest for the Sangraal, SG-1 must join forces with their enemy and face a real-life dragon.

The SG-1 team hadn't counted on a real dragon as a guardian until one flies out, breathing fire. However, Daniel thinks the Sangraal probably is a hologram. They escape, but the dragon follows them outside. Ba'al admits not to know its secret name, while Daniel believes that the name probably holds power over it. While they guess, Cam thinks of luring the dragon to blow it up, but the C4 barely impresses its digestion. Daniel makes it disappear by using Morgan le Fay's name in Ancient, Ganos Lal. They find it had guarded the frozen 'grave' of the realm's arch-magician, Merlin (or rather, Myrrdin). Vala accidentally triggers a mechanism which revives Merlin when she approaches an Ancient repository device. In the meantime, the team is transported to another planet via the obelisk by the gate outside. Sam surmises that the gate and obelisk are programmed to dial automatically every few hours and transport them to a set of planets that are cut off from the rest of the gate system. Unfortunately, they can't dial out to any other planets either while the program is operating. When he comes to, Merlin seems to confuse the team and Ba'al, with Arthurian characters, but once convinced they are on the same side, he goes to work with the Ancient device to create the Sangraal. Merlin dies at the device, wishing them good luck and referring to one last task. Ba'al's stargate programming skills now seem their only chance. Daniel tries the Ancient repository device himself, but is knocked unconscious. Meanwhile, Adria keeps searching for them via the stargate dialing program on different planets- each time a bit quicker- being one planet behind them. While she is searching, the team is once again transported to another planet, minus Merlin's body. Daniel awakens with valuable memories from Merlin and tries to construct the Sangraal using the repository device again, in exhaustingly intense phases, and finds it also gives him telekinetic powers. It also messes with Daniel's mind, having two different personalities and memories present (his own and Merlin's). Before he can finish the work, Sam and Ba'al disengage the dialing device, just as Adria's Ori troops arrive, allowing SG-1 to escape. Adria is able to capture Daniel before he can escape as well.

When an entire people may suffer the fatal wrath of a Prior of the Ori for not converting, General Landry orders Carter to try out an experimental device based on Merlin's technology to transport their whole village. The test works, but before they can activate it on a sufficiently large scale, an Ori force takes the village, wounds Sam and kills villagers near the Stargate before Vala's very eyes. Her husband, Tomin, captures her but claims to not love her. He is ordered, as punishment for being deceived by her, to re-educate her. Sam and Cam are able to activate the functioning part of the device, so their building is cloaked from the Ori, who threaten the village leaders and discover and arrest Teal'c. Even after the remaining villagers bow in submission, the Prior decides to destroy everyone since he couldn't find Sam, which makes Tomin doubt his faith, inform Vala, and confront the Prior. The villagers want to sacrifice Teal'c, but one leader stops them. Having seen the Prior destroy the village, Tomin sends Vala down, where she sees if Carter had managed, just in time, to get the device working...

During a failed experiment, Samantha is transported into a parallel universe where she cloaks Earth to save it from an Ori attack. Getting back to her own universe is not met with sympathy.

Daniel Jackson, who was left behind fighting off Adria while the other SG-1 members escaped through the Stargate, is found working as a Prior: the best in the business, who doesn't need to use any threats to talk people into conversion to Origin. Hoping there is still some of his personality left, the team (plus General Jack O'Neill) kidnaps him. Daniel explains how he temporarily has Merlin's personality and knowledge in himself, and had deliberately allowed Adria to turn him into a Prior, while delaying to finish Merlin's weapon she'd wanted, meanwhile hoping to get an Ori ship for Earth's side. But time is running out, since the team took unexpectedly long to capture him. Still, the generals, Carter, and Vala are most reluctant to go along with releasing him and opening the wormhole he needs to bring the weapon through. Even the White House wants to kill him, or at best, keep him in stasis until he is reverted to his human nature by Merlin's genetic manipulation. But then his plan is wasted- unless the others can be trained to do it in his place (so only they are at risk, not the entire galaxy in case Daniel is Adria's Trojan Horse). After giving them the necessary information, Daniel suddenly frees himself while Richard Woolsey is with him and takes control of a space ship after beaming up Jack too, just after the others have undertaken their mission to Adria's lair, where Daniel, about to be genetically reverted, arrives just in time to tip the balance in their favor.

SG-1 blows up three transport ships in a row; Netan puts a price on their heads. General Landry grants the team members spare time on Earth. Daniel spends it researching in a library, where he meets a bounty hunter who tries to seduce him, then switches to her handgun... but is taken out by a bus. Sam gives a lecture on Air Force technological progress together with Dr. Bill Lee; a sniper nearly misses, but is taken out with an experimental weapon they'd brought along to demonstrate. Teal'c is injured by surprise at a Jaffa camp and successfully traps the killer to try again. Cam goes to his Kansas high school reunion and Vala succeeds in making him bring her along, pretending to be his accountant and partner. His still sexy former flame he'd believed out of his reach, Amy Vandenberg, is initially scared off by Vala, but, divorced and interested, explains she still has a secret crush on him. Alien bounty hunter Odai Ventrell assumes numerous classmates' appearances to kill him. Vala's failed rescue gets them both captured publicly, so he threatens to kill off reunion guests unless the other SG-1 members take their place, but they trick him using Chimera technology; they hope Netan's failure to eliminate them will rekindle the power struggle and Odai reacts surprisingly.

When SG-1, minus Carter, investigates a previously unexplored planet expecting to find themselves in a pyramid, they are astounded to find themselves in a museum. Finding a party occurring in the lobby, they decide to leave and make first contact later, but they find that the DHD is a replica and thus incapable of getting them home. They are discovered and believed to be rebels and are forced to take hostages to buy time for their escape.

Teal'c and Bra'tac are among the numerous victims -though only wounded- of several bomb attacks killing 32 men at a summit in the Jaffa settlement Dar Eshkalon. As soon as physically able, Teal'c swears to avenge them personally, suspecting the honor-less, ambitious warrior Arkad; General Landry refuses to sanction a killing mission without solid proof, but cannot stop Teal'c from going it alone. Bra'tac explains Arkad's sinister past to Daniel, including the possibility of murdering Teal'c's mother. Information from the resistance on another planet indicates Arkad is in league with the Ori and plans to attack Earth. Arkad comes to meet General Landry, offering to help defend Earth against the Ori, denying any part in the bombings, while defending Origin, incriminating a Jaffa sect. SG-1 is now ordered to find and stop at all cost Teal'c, who is using torture. But Teal'c, committed to killing Arkad, reaches his place, but is wounded, captured, and made to duel Arkad after it is confirmed he had killed Teal'c's parents.

Stargate Command gets a video message from Vala's extremely unreliable father, Jacek, on the planet Robak; he claims to know about the late Arkad's plans to attack and blow up Earth, even about the several cloaked, Naquadah-laden cargo ships in orbit, and offers details in exchange for sanctuary. General Landry asks Dr. Lam to help him resume contact with her mother, Kim, his ex-wife. Even after the cargoes are found and blown up, Vala abhors her dad's entry. The general asks her to go easy on him, realizing that he, too, neglected his daughter because of his career, even if Jacek's neglect was just criminal. When Cam and Daniel go tell Jacek he shouldn't scam people, he tricks them into talking to Vala for him. Vala goes over just for catharsis, telling him she's through picking up the pieces of his tricks, and he certainly keeps scamming - as Daniel also finds - even with Terak, a Jaffa from an escaped cargo ship, who hopes to sell the Naquadah. When they are apprehended, Jacek promises to help track it and override the rigging of the cargo ship. The Jaffa wait for Jacek and Vala, intending to eliminate them now that Terak is gone, but SG-1 saves them. Since there never was an override, Jacek cheerfully flies away alone in the cargo ship, ignoring that his treachery was anticipated: it's a decoy.

Vala gambles, wins a cargo ship, but is found cheating; then Adria appears, throws everyone out and claims she has a new Ori fleet and an operational intergalactic Stargate. Vala tells her scary daughter how she helped Daniel, after a dream, reading the mysterious clava thessara-symbol's mystery, which led to a single planet address, where Athena's treasure house must be; after a disastrous visit there, the team refused to follow the next interpretation, fearing it's just a trap set up by Adria, so Vala is declared a security risk, grounded and confined to Area 51, but escapes through the Stargate. Adria takes her along as she hears the team still plans to visit the address, by starship. Upon arrival, they are trapped by SG-1, which however finds itself surrounded by lord Ba'al's troops. Ba'al uses the rings to beam up Adria into an electromagnetic cage in his starship. Back on Earth, General Landry worries what damage the two might do together and wants Adria back. Daniel and Sam now show Vala she has been implanted by Galaran technology with fake recollections of her entire adventure 'til the meeting with Adria. Even though she claims that's impossible, Ba'al is confident he can take control over Adria's loyal Ori troops through her- by implanting a symbiote. The team finds Ba'al's Jaffa and clones killed by symbiote poison, except one Jaffa who secretly used tretonin. The team ring-beams from the cloaked Odyssey starship into Ba'al's, shoots him and captures Adria, but back on Earth, she is found to be under the control of his symbiote. Instead of just killing the evil double, they contact the Tok'ra which send Ta'Seem to extract the symbiote and replace it with a Tok'ra one, but Ba'al manages to poison Adria, who has to be put down. Suddenly Adria wakes up, uses mind-power barricading herself in the sick bay with Vala, tells them she needs time to prepare for ascension, as Daniel guesses outside, and succeeds before the team can cut their way in by blow torch. Nobody knows what this will mean for the future, especially as it remains uncertain whether the Ori are still alive. If not, she may have gained all their former powers, and at least one clone of Ba'al still remains...

General Landry accompanies SG-1 on a mission to collect the knowledge of the Asgard. When the Ori show up, however, Sam is forced to evacuate the crew. Landry and SG-1 stay aboard, but are stuck helpless in a time dilation field for decades.

When an SG geological exploration mission runs into deadly conflict with an indigenous Unas clan, Daniel gets Chaka to help seek an accord with it.

As Jackson suffers from a fatal dose of radiation, he struggles with the value of his life while his friends deal with the emotional and diplomatic repercussions.

While on an archaeological dig at the original Goa'uld home world, Daniel is captured by a young Unas. He tries to communicate with it and slowly builds a rapport. Meanwhile, SG-1 comes to the planet to find Daniel and they soon realise that some of the SG-team members there may have been taken over by Goa'uld. Will they be able to discover which ones in time to rescue Daniel?

The SGC send a MALP to a huge pyramid and inside they discover a crystal skull like the one Jackson's grandfather found many years before. SG1 visit the planet and whilst Daniel is looking into the eyes of the skull, as his grandfather did, an energy field envelops him. Teal'c fires his Zat at the skull, but Daniel has disappeared. Carter collapses and the team minus Daniel return to the SGC. Teal'c returns to collect the crystal skull, but will he be able to find Daniel?

The Stargate team must justify the project's continuation when a doubtful senator, Head of the Congressional Military Appropriations Committee, comes to review the project's performance.

The discovery of the Stargate creates a war between two nations on the planet Tegalus with Daniel in the middle of it.

Agent Barrett of the NID calls SG-1 to Los Angeles for a consult on a mass murdering of a rogue sleeper cell by a young woman. There they find many Goa'uld artifacts relating to Sekhmet, a subordinate of Ra. But how this operation is related to the Goa'uld eludes SG-1.

When one of Daniel's professors dies in a lab explosion which might be related to the Goa'uld, he comes back to Chicago to investigate what really happened.

When Daniel's Unas friend, Chaka, is captured by another world's slavers, SG-1 goes to that world to rescue him.

In a Tok'ra plan to wipe out the Goa'uld, Daniel goes undercover as Yu's servant to release a poison at a meeting of the system lords. Meanwhile a Goa'uld attack on the Tok'ra base leaves the rest of SG-1 with their hands full.