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.

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?!?

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.

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.

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.

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.

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.

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.

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?

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.

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...

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?

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.

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

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.

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.

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?!?

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.

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.

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.

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.