The fleet has found a source of water, but who will take on the difficult and dangerous job of mining it from the icy planet? Commander Adama and President Roslin send Lee to the Astral Queen, a prisoner transport ship, with an offer for its inmates: Volunteer for this mission and earn "freedom points".

When a new copy of Doral, a Cylon who had been previously exposed while serving as the Galactica's public-relations officer, sneaks aboard and blows himself up, killing three people, Commander Adama and President Roslin must finally make public the terrifying secret known only to a select few: Cylons now look like humans.

President Roslin's fears that Commander Adama is a Cylon are stoked when she learns he's making secret wireless calls to other ships. Then, to make things worse, a single Cylon raider appears near the Galactica and begins acting strangely after being damaged in battle.

While flying a supply patrol, Crashdown and Sharon Valerii discover a bountiful planet that can support human life. Indeed, it might be Kobol, the legendary "home of the gods." The discovery prompts Commander Adama to send a ground team to investigate; it also gives new life to President Roslin's belief that she is a tool of destiny and that this discovery, like her rapidly spreading cancer, is part of an ancient prophecy.

When Commander Adama learns that Kara disobeyed orders and Jumped to Caprica on orders from President Roslin, he demands the president's resignation, with the implied threat of a military coup. Roslin refuses his demand and sparks a confrontation.

With Adama out of action, Colonel Tigh takes his position as commander of the Galactica. Boomer is in jail, and the cat's out of the bag - she's a Cylon.

President Roslin's fragile coalition is put to the test in the first part of a two-part story. Apollo, who has sided with Roslin, runs into a conflict with Zarek and his accomplice Meier.

Adama heads to Kobol to find Roslin, reassembles the fleet and heads down to Kobol himself to find the presidential party in search of the "Tomb of Athena" which allegedly leads to Earth. Apollo hangs out with Starbuck , Zarek tries to keep his cronie off plotting with Boomer who is unaware of tension building between Helo and Tyrol.

The Battlestars Galactica and Pegasus face a new Cylon target, a "Resurrection" ship, while a power struggle threatens to result in all-out war among the human fleet.

The struggle between Adama and Cain is temporarily put on hold while the two Battlestars combine forces for an assault on the Cylon Resurrection Ship. Apollo faces a momentous decision and Baltar takes an interest in Gina, the Cylon prisoner.

Pegasus' new commander Fisk is murdered by black marketeers, and Lee is charged with solving the crime. Roslin seeks to stamp out the black market by introducing new trade regulations.

Apollo assists in the search for a missing Raptor team as the new commander of the Pegasus grows increasingly unstable.

Chief Tyrol is plagued by terrifying dreams and seeks the aid of a priest. Kara leads a rescue mission to Caprica. Roslin and Baltar go head-to-head in a presidential debate that changes dramatically with the discovery of a habitable planet.

When Baltar wins the vote, Roslin considers stealing the election because she believes he is a Cylon collaborator.

Tigh, Tyrol and Anders lead the Resistance on New Caprica to increasingly deadly attacks against the Cylons. Kara finds herself trapped in a new life with Leoben Conoy, and Duck makes a fateful decision. Meanwhile on Galactica, Adama struggles with the question of whether to return to New Caprica to mount a rescue attempt.

Tyrol participates in the Circle, a secret tribunal on Galactica that tries and convicts in absentia those accused of collaborating with the Cylons during the Occupation. The death sentences--administered without the knowledge of Roslin or Adama--begin to weigh on Tyrol's conscience. Baltar faces a similar jury among the Cylons, who must decide whether he is allowed to stay with them.

A figure from Adama's past returns to haunt him. His return raises questions about why the Cylons launched their initial attack against the Twelve Colonies.

Now on board Galactica, Baltar faces charges of treason. He contemplates suicide with the help of Number Six. Questions remain about his true identity. Is he a Cylon or isn't he? Apollo shows off the new drinking establishment on Galactica, Joe's Bar, to Tyrol. Apollo thinks about Kara and wonders whether his marriage to Dee is worth saving.

Kara continues to have dreams about Leoben Conoy and the mandala she painted at her old apartment on Caprica. While on patrol in her Viper, she encounters a Cylon Heavy Raider. When Tyrol cannot verify Kara's claim that the Cylon ship struck the Viper, Admiral Adama and Lee become concerned about her mental stability.

As Baltar's trial comes to a conclusion, key members of the fleet discover that they may be the Final Five Cylons. Tigh attempts to decipher the strange music he is hearing in his head, while a Cylon fleet approaches.

Kara struggles with the foreboding prediction of the Cylon Hybrid, while Adama and the Colonial fleet face despair over their shocking discovery.

Kara feels lost while she struggles to cope with Sam's continued coma, meanwhile Boomer faces charges of treason from the Cylons onboard the base ship who blame her for voting against her model during the civil war causing the deaths of thousands of Cylons.

With Galactica on the verge of falling apart, Admiral Adama readies the ship for what could be its final mission, as Baltar's Six warns that humanity's final chapter is near.

Adama and the Galactica crew stake the survival of the human race on their plan to rescue Hera from the Cylon colony in this, the series finale.