As its fuel supply dwindles, the fleet must seek out a new supply of tylium ore or risk becoming sitting ducks to any Cylon attack. A recon patrol finds an asteroid full of the fuel, but there’s a catch — the Cylons have found it first and established a heavily guarded refining plant.
A woman takes hostages on Cloud Nine and demands that Adama turn over Sharon in order to avenge her husband’s death at the hands of the Cylons.
Tigh must decide the fate of his wife Ellen after the assistance she rendered to the Cylons. Lee struggles with his assignment to protect the civilian fleet on its journey toward Earth while Adama returns to New Caprica with just the Galactica. The Resistance coordinates an attack on the Cylons just as Galactica arrives. As the Cylons begin to lose control, Number Three vows to put a final end to the New Caprican experiment.
When Lt. Kara Thrace goes missing in action after encountering a Cylon patrol while on a training mission, Commander Adama feels responsible — especially in light of her recent admission that she blames herself for his son Zak’s death.
The Colonial fleet faces starvation when the food-processing machines are contaminated. Kat plays a vital role in the success or failure of the “Passage” through space.
The dying President Roslin and the aggressive Viper pilot Kara Thrace try to accept the new terms of the relationship with the Cylons.
The Cylons learn that the Final Five are in the Colonial fleet. Some of the Cylons want the Cavil model to stop lobotomizing the Raider ships. Starbuck desperately tries to convince the others that the fleet is going the wrong way in their search for Earth.
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.
As Sam Anders recovers from his head injury onboard the Galactica, he begins to remember events from ancient Earth. The Final Cylon struggles with the fallout from the Final Five’s former plans. One of the humanoid Cylons vows to get revenge for being created in the image of Man. Tyrol informs Admiral Adama about the extensive structural damage on the Galactica.
Apollo formulates a plan that threatens the very existence of the Cylon culture. Adama and Roslin must decide whether to follow through on the plan to use a biological weapon against the Cylons. D’Anna Biers (Number Three) believes Baltar knows who created the virus that infected and disabled the Cylon baseship. She is willing to take extreme measures to learn the truth.
The Sagittarons allege that a doctor is discriminating against them. As Helo investigates, he becomes concerned that the doctor may even be murdering patients. Meanwhile, Athena unwittingly brings Hera to the doctor for treatment.
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”.
As President Roslin nears death, Dr. Gaius Baltar must be groomed for the worst case scenario. Roslin orders the death of Sharon’s unborn child. A sabotaged Viper leads to an investigation that uncovers a movement of people seeking peace with the Cylons.
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.
Chief Tyrol and his wife Cally become trapped in a malfunctioning airlock. Adama remembers his late wife Carolanne as he marks his wedding anniversary. His relationship with President Roslin continues to become more friendly and personal.
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.
Battlestar Galactica was not the only Battlestar to have survived the cylon attack, The Battlestar Pegasus also survived.
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 Roslin fight for the hearts and minds of the fleet’s population, as Starbuck finds herself trapped in a supposed resistance hospital.
Sharon helps the Resistance on New Caprica as Adama leads Galactica on a dangerous rescue operation. Tyrol races to save Cally from the execution squad. Meanwhile Anders uncovers treachery among the humans. Number Three meets the Oracle Selloi after having strange dreams about the temple.
