When the initial Cylon attack against the Twelve Colonies fails to achieve complete extermination of human life as planned, twin Number Ones (Cavils) embedded on Galactica and Caprica must improvise to destroy the human survivors.

Edward James Olmosas Commander William Adama
Dean Stockwellas Brother Cavil
Michael Truccoas Samuel Anders
Grace Parkas Lt. Sharon 'Boomer' Valerii
Michael Hoganas Colonel Saul Tigh
Callum Keith Rennieas Leoben Conoy
Kate Vernonas Ellen Tigh
Rick Worthyas Simon
Lymari Nadalas Giana O'Neill
Matthew Bennettas Aaron Doral