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.

Adama stages a boxing tournament on the Galactica to help the crew relax. The competitive atmosphere sets off a brutal match between Kara and Lee. Flashbacks from New Caprica reveal the origin and nature of their dispute.

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.

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.

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.

A crazed Cylon Raider attacks the Colonial fleet in a series of hit-and-run attacks. Overworked Viper pilots must defend a mining operation from this Raider that they nickname "Scar."

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.

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.

When Baltar's representatives face assassination attempts, Adama asks Lee to protect Baltar's lawyer. After taking on the assignment, Lee seeks to play an active role in Baltar's defense.

Kara Thrace seeks her own path in the search for Earth while the Cylons face the threat of sentient Centurions. A member of Galactica's crew learns a dark secret about a loved one.

Specialist Tyrol continues to sink into despair after his recent loss. He becomes curious about Gaius Baltar's sermons and the following he has attracted. The crew of the Demetrius grow concerned about Kara's mental stability as an old enemy arrives with a tempting offer.

Ellen escapes from Cavil only to face a momentous choice regarding the 13th Tribe and the Final Five Cylons.

Gaius Baltar sets off a debate on religious freedom when he promotes his belief in a single God.

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.

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.

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

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.

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.

Amid a heated labor dispute, Tyrol asks the imprisoned Baltar for advice. Seelix becomes involved after she is turned down for flight training.

With President Roslin missing along with the cylon base ship a new president must be decided on. Galactica goes on a search for the missing base ship and the Galactica crew members that were on board.

Lt. Sharon Valerii wakes up soaking wet in the tool room with an explosive charge in her duffel bag. Shortly afterward, a mysterious explosion destroys all the port-side water tanks on Galactica, creating a crisis for the entire fleet. Sharon can't remember a thing, but all the evidence points to her as a saboteur. She confesses her concern to Chief Tyrol, but he can't believe she's responsible.

When Baltar and the Number Six who lives in his head have a falling out, she abandons him, only to surface a short while later aboard the Galactica. But now she's called Shelley Godfrey, everyone can see her, and she's telling them that she has evidence, passed on by the late Dr. Amarak, that will prove Baltar sold out the human race to the Cylons.

Adama and Roslin fight for the hearts and minds of the fleet's population, as Starbuck finds herself trapped in a supposed resistance hospital.