The Cylons have not been around for over 40 years since their last brush with humanity. But now they have come back with a vengeance, and are on a mission to wipe out their creators. Using their new technology, they start to disable human ships, kill their pilots and lay waste to the Twelve Colonies of Man. The attack forces Commander Adama to bring his old battlestar, the Galactica, into use again, and the crew begins to collect survivors. But the Cylons fight back with the deadly ‘Number Six’, a Cylon in the form of a human being. She messes with scientist Dr Baltar’s brain and threatens the future of humankind.