There's a party on Galactica's flight deck as Flat-Top just had his thousandth landing. Something goes terribly wrong however when a drone accidentally goes off and explodes in a group of pilots. 13 are dead. During the ceremony Kara Thrace starts thinking about her dead fiancée Zak Adama. And those memories even get clearer when Adama orders her to start training new pilots. She seems very uncomfortable in doing so. The favor she did for Zak by letting him pass basic flight seems to bother her more and more. Angrily she stops training pilots after just one day. Meanwhile on Cylon-occupied Caprica Helo and Cylon-Sharon find a bomb shelter in a restaurant. It seems like a good place to stay for a while. There's food, water and anti-radiation medication in abundance.

Starbuck has been shot down over a barren moon, and must be rescued before she runs out of oxygen. Adama become obsessed with trying to save her even when all hope seems lost, putting the fleet at risk. Meanwhile, Starbuck finds the Cylon Raider she shot down, and tries to learn how to fly it so she can escape.

A humanoid Cylon straps himself with explosives and commits a suicide bombing in a crowded hallway on Galactica. Roslin and Adama are forced to publicly reveal that the Cylons now have models that look like humans, and a wave of paranoia spreads over the fleet as everyone starts being suspected of being a Cylon.

The fleet is running out of tylium fuel and will soon not have enough to keep running from the Cylons, when they find an asteroid with several years worth of tylium ore...unfortunately, the Cylons have already built a mining base on it.

Galactica stumbles upon Kobol, the long-lost home world of humanity that the 13 Tribes came from, which legend says holds the only clues to the location of Earth. Roslin convinces Starbuck to steal the captured Cylon raider and return to Cylon-occupied Caprica with it to retrieve a religious artifact that will unlock the secrets on Kobol.

As the premiere for the second season unfolds, Adama lay dying leaving Tigh in command. Lee and Roslin have been sent to the brig. An emergency jump goes wrong leaving the Galactica alone in space without the fleet.

A Cylon virus is interfering with Galactica's power supply, while Cylon centurions are heading for crucial systems. Somehow they must be stopped.

Tigh's decision to impose martial law is protested in the fleet as well as on Galactica. On Caprica, Helo and Starbuck meet other humans.

Starbuck, Helo and Boomer bring back the Arrow of Apollo, but Boomer doesn't seem welcome. Commander Adama wants to keep the fleet divided and appoints a new CAG.

Journalist D'Anna Biers is making an item on the Gideon incident, when she's asked by Adama and Roslin to film daily life on Galactica.

While Tyrol decides to start building a new fighter, the Cylon virus is rearing its ugly head again. Boomer says it means a large Cylon attack is imminent.

Adama and Cain find common ground when Starbuck returns with footage of the Cylon ship. Roslin negotiates a temporary truce, while Starbuck plans an attack.

President Roslin, who is about to die, believes Sharon's baby is dangerous and orders it must die. Meanwhile, a terrorist group inside the fleet starts to ask for a peace negotiation with the cylons.

This is an episode about loss. Kat and Starbuck confront each other about their piloting skills and each vow to kill Scar (a Cylon spaceship) before the other.

The attack to rescue everyone on New Caprica begins. The Galactica encounters four rather than the expected two Cylon Basestars. The end appears in sight but they get help from a welcome but unexpected source. On the planet below, Tyrol and Anders lead the attack to free everyone from the prison. Anders finds Starbuck but she won't leave without Kacey. Her successful return to the Galactica results in mixed emotions. Colonel Tigh must decide what to do about his wife Ellen after she admits to giving the rendezvous coordinates to the Cylons. Hera doesn't make it off the planet.

Baltar learns from Caprica Six of their ability to project themselves and imagine different surroundings which leads him to wonder if he too is a Cylon. He has told the Cylons what he knows about the location of Earth and they dispatch a Basestar to investigate. In the end, the survey ship is infected with a virus killing everyone aboard. Aboard the Galactica, Lt. Gaeta has been reviewing Baltar's work in deciphering the map they recovered on Kobol. He too thinks he knows what it all means. Of greater concern however is the wedge between those who stayed with the fleet and those who were on the ground fighting the Cylons. Starbuck and Colonel Tigh in particular are quite vocal in complaining about those who stayed behind and it's left to Admiral Adama to lay down the law.

When a group of ill Cylons from the infected Basestar is brought to Galactica, Lee discovers a way to solve the Cylon problem forever - by destroying the whole Cylon race. Meanwhile, D'anna's acts to discover if Baltar is reliable will forge an unusual relationship.

A look at the events that took place during the year-long gap from the storyline in the Season Two finale. The story reveals the reasons for the rift between Kara ("Starbuck") and Lee ("Apollo").

The Colonial fleet makes a harrowing journey. Kat plays a vital role in the success or failure of the passage.

The Chief and his wife get trapped in an airlock on a routine maintenance job, while the Admiral copes with his wedding anniversary and the memories of his ex-wife.

The Admiral is forced to make the decision of whether to ground Kara Thrace when she begins to show signs of an oncoming nervous breakdown.

Besides having to deal with the loss of Kara Thrace, the crew of the Galactica is also charged with the security surrounding the trial of Dr. Baltar and his defense attorney, who is replacing one lawyer that has already been killed.

Baltar goes on trial for his life, and it affects everyone from Lee on up to the president.

Starbuck (Katee Sackhoff) and Laura Roslin (Mary McDonnell) face off with a gun between them, Lee Adama (Jamie Bamber) says goodbye to the Galactica, violent conflict breaks out between the seven models aboard Cylon Basestar, and Gaius Baltar (James Callis) is directly pulled into the "Final Five" situation.

When a Heavy-Raider manned by Leoben Conoy docks aboard the Demetrius, confrontations form between the crew over the possibility of a truce with Cylon rebels, while Starbuck puts her trust in an old enemy.

A vicious injury ends the mutiny attempt aboard the Demetrius, Kara leads her crew to the Cylon rebel's Basestar, and Roslin begins to understand Gaius Baltar's appeal to his followers. Meanwhile, Anders attempts to secretly find answers to his purpose as a member of the Final Five.

A shaky alliance between the Colonial Fleet and Cylon rebels is put to the test when the two groups combine efforts to take out a Cylon "Resurrection Hub". Meanwhile, Athena loses control when Hera becomes unnaturally drawn to Natalie.

The Hybrid keeps jumping the basestar, and Roslin has visions. The three, D'Anna, is un-boxed. Humans and Cylons engage in a battle to destroy the Resurrection Hub. Baltar is badly wounded and Roslin has to decide whether or not to help him.

D'Anna demands that the four Cylons in the fleet be sent to the basestar. Only Tory goes, while the remaining three are suddenly drawn to Kara's Viper by the music. The route to Earth is finally found.

Adama considers Saul and Tyrol's suggestion that the Fleet should integrate Cylon jump technology since it will triple the distance they will be able to cover before they run out of fuel. But the Cylon's condition is that they will be allowed to join the Fleet, for safety against Cavil, who's still out there. Ultimately, the decision is up to President Roslin, but Zarek calls the Quorum and gets them to carry the motion that no Cylon be allowed aboard any Colonial vessel unless permitted by the ship's captain. Tyrol learns from Dr. Cottle that Cally had their child tested and the results indicated that Tyrol is not the father - therefore the child is fully human. Roslin starts her climb up from the depths of despair she had fallen to soon after the Fleet found Earth.

The Fleet refuses to cooperate with Cylon engineers and Adama decides to put an end to it. He sends the Quorum a message stating that unless they wish to join Zarek in the cell, they get their people in line. However, Gaeta has already freed Zarek with the help of other would-be-revolutionists. They allow Zarek to leave Galactica on a raptor. He lands on Colonial One and enters a gathering of the Quorum. Meanwhile, Anders gets ambushed and captured. At the CIC, Gaeta cleverly manipulates everyone else until the time is at hand for the revolution to begin.

Roslin is on board a raptor en route to the Rebel Cylon Base Star, but Gaeta has ordered to engage and destroy it. The marines have used a stun grenade on Adama and Tigh. Roslin manages to get a wireless transmission out for everyone to hear and learn what Gaeta has done. She and the others barely make it to the Base Star, where she convinces Tory and the other Cylons to use the Fleet as a cover in order to prevent Gaeta from attacking it. She also believes that Adama will be able to save the rest of the Final Four. Temporarily safe, the Rebel Cylons start voting on whether they should just jump away and count their losses. Adama is brought before Gaeta and Tigh is thrown to the brig with Caprica Six, Anders, Athena, Helo and their child Hera. Zarek comes aboard Galactica on Colonial One with the Quorum. At Gaeta's insisting, Zarek agrees to put Adama on trial for treason, with Romo Lampkin assigned as his defence lawyer. There's just one problem: The Quorum refuses to recognize Zarek's authority. However, Zarek is hell-bent on following his "The truth is told by those left standing" maxim. Only Tyrol, who's alone, and Lee, whose with Starbuck, are Galactica's last hope.

Ellen and Boomer travel to the Galactica. Saul is entranced at the sight of his wife while Adama puts Boomer in the brig. Ellen is not so pleased when she learns that Caprica Six is pregnant by Saul. Her interference and jealousy leads Six to have a miscarriage. Sam Anders survived the operation but now seems to be brain dead. Ellen is disappointed that the Final Five cannot be completely reunited. By majority vote, the Five agree that they will go off on their own, leaving the Colonial Fleet behind. Adama has agreed to have the cracks in the Galactica's hull repaired using a Cylon living resin.

Kara meets a pianist who reminds her of her father. She tries to play a melody she remembers from her childhood, and a drawing made by Hera helps her. Meanwhile, Boomer is to be tried for treason. Tyrol takes her side, and helps her escape.

With Hera now likely in the hands of John Cavil, Admiral Adama sends out search teams to locate The Colony, the Cylon home world if you will, that Ellen Tigh says is the only place she imagines she could be. Adama reluctantly comes to the conclusion that the Galactica has reached the end of its days. He orders all repair activities halted and decides to strip the ship and share everything that is salvageable with the rest of the fleet. Starbuck meanwhile shares with Gaius Baltar what she found on the uninhabitable Earth. He subsequently - and quite publicly - proclaims her to be an angel.

The Colony is located sitting on the edge of a black hole with only one point of entry in what is a very large debris field. Knowing that the Galactica has reached the end of the line, Admiral Adama asks for volunteers to mount a raid on the Cylon base, realizing it may be the ship's last jump. In flashbacks prior to the Cylon invasion, key moments in the lives of several of the crew are presented. These include include the first time Kara Thrace and Lee Adama meet; Admiral Adama's struggle with his decision to retire from the colonial fleet; Gaius Baltar's relationship with his father and his developing relationship with Caprica Six; and Sam Anders discussing the motivation behind his professional sports career.

A stripped down Galactica attacks the Cylon's Colony ship in the hopes of rescuing Hera. The meaning of the shared dream in the Opera House on Kobol is revealed. Sam Anders is moved in his Hybrid tank to the CIC in the hopes that he will be able to assist the combatants. Their mission complete, Admiral Adama orders Starbuck to pick a destination - any destination - to which the ship can jump to get out of there. With that, the meaning of the tune and the musical notes are explained. Having successfully jumped, the old Galactica has truly reached the end of it's life. A planet capable of sustaining life is found and Lee Adama makes a radical proposal for the future of humankind. In a flash forward far into the future, Hera's importance to the human race is revealed.

As conflicts reach a climax, Cylons and humans face a stark choice.