Maren Jensen

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

Following the lead of President Roslin and Tom Zarek, more than one-third of the fleet has split from the Galactica and jumped into orbit around Kobol.

Following the lead of President Roslin (Mary McDonnell) and Tom Zarek (Richard Hatch), more than one-third of the fleet has split from the Galactica and jumped into orbit around Kobol. Tensions arise within the rebel ranks on the Astral Queen as Zarek and his security Chief, Meier (James Remar), face off with Lee Adama (Jamie Bamber). Those tensions increase when Kara (Katee Sackhoff) and Helo (Tahmoh Penikett) return from Caprica with Sharon (Grace Park), who is now pregnant and a dead ringer for the Cylon who tried to assassinate Commander Adama. Roslin orders Sharon put to death, but after meeting with her, she learns that the Cylon might be their best hope for finding the Tomb of Athena and the route to Earth. Doubt nags at Roslin, however: is Sharon motivated by love for Helo, or by a desire to betray her captors? Regardless, she's a key player in Roslin's team as it lands on Kobol. With Zarek and Meier plotting fresh treacheries, the prophecies continue to unfold in bloody fashion. On the Galactica, Adama (Edward James Olmos) and Col. Tigh (Michael Hogan) weigh their losses and rebuild the air group's chain of command, which has been plunged into disarray by the defections of Lee and Kara. Adama selects Lt. George "Catman" Birch (Ben Ayres) to replace Lee as CAG (Commander, Air Group). Birch's first day on the job begins with a harrowing mishap during Viper-pilot training exercise, and then he turns a routine refueling operation into a near-disaster. Following an uncomfortable meeting with Dualla (Kandyse McClure), Adama is forced to admit that there is no substitute for the people the fleet has lost. He orders a Raptor to be prepped to take him and a small team back to Kobol, so that he can find Roslin and Lee and put the fleet back together. Also available on NBC

A Cylon virus has penetrated the Galactica's computers, while Cylon Centurions have boarded and are battling toward the ship’s vulnerable centers.