Sharon informs Adama that the Galatica has been infected with a computer virus that is tampering with the basic ship functions and is scanning them for weaknesses. All this is preparation for a major assault by the Cylon Raiders. So with the clock ticking

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."

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

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.

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.