Mark Corley, a Los Angeles police detective, helps his estranged son, Trent, out of jail just as an alien invasion begins. The entire population of the city is sucked into various spaceships by a blue light. Mark leads a group of surviving humans through underground subway tunnels to escape, though most of the humans are killed or abducted one by one. The survivors – Mark, Trent, transit operator Audrey, and a homeless man known only as "Sarge", who is immune to the blue light due to his blindness – escape to the marina following its nuclear destruction, only to be abducted into the alien flagship by a towering alien tanker.