Battlestar Galactica Episode 2.02 Valley of Darkness

The Galactica has succeeded in reuniting with the fleet, but it has paid a terrible price: A Cylon computer virus has penetrated its computers, robbing the ship of power, and Cylon Centurions have boarded the Galactica and are battling their way to the ship's vulnerable centers.

Lee Adama, in the brig with President Roslin, persuades some marines to release them. He orders Billy and Vedder to take the president to the sickbay disaster shelter, where she'll be safe, and heads off with a squad of marines to defend the ship's magazines.

In the CIC, however, Col. Tigh knows from bitter experience what the Cylons are planning. The Centurions aren't going to blow up the ship; they're going to kill the crew by venting the ship's air and then turn its guns on the rest of the fleet. And only Lee - whom Tigh despises for his "disloyalty" to Commander Adama (i.e., support for the president) - and his small squad of marines are in position to stop the Cylon boarding party.

Meanwhile, on Cylon-occupied Caprica, Starbuck and Helo break into her old apartment and fire up her old pickup truck.

Light-years away on Kobol, Chief Tyrol and his crew return from their risky mission to get medical supplies for Socinus, only to realize that the wounded man isn't going make it. Number Six warns Baltar that Socinus won't be the last of the stranded Raptor crew to die - and that of all the humans, Baltar alone will live to see Earth.