All of this has happened before

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.

The history and adventures of the Battlestar Pegasus, from shortly before the Cylon invasion to shortly after Lee Adama is made commander. The story is told through the eyes of and largely focuses on one particular member of Pegasus's crew, Kendra Shaw.