The Battlestar Galactica and its ragtag fleet of ships finally locate the planet Earth, only to discover that the Cylons have followed them there. Captain Troy and Lieutenant Dillon are dispatched to speak with nuclear physicist Donald Mortinson and obtain his help by gathering scientists to defend Earth against the Cylon invasion. Arrested as anti-nuclear demonstrators, Troy and Dillon befriend feisty television reporter Jamie Hamilton who helps them understand Earth culture. Troy are Dillon are then dispatched to find a crashed Cylon Raider, only to find that the Cylons have stumbled into a Halloween party.