Captain Colter Stevens wakes disoriented in the body of a stranger, aboard a Chicago commuter train that, eight minutes later, is blown apart by a bomb. He discovers that he is part of a military experiment called Source Code, capable of inserting his consciousness into the final minutes of a victim's life, and that his mission is to relive that span over and over until he identifies the terrorist before he strikes again. As he unravels the puzzle, he is torn between duty and the desire to save a woman already doomed. Duncan Jones directs an agile, ingenious science-fiction thriller about time, identity and sacrifice.