A man (Jake Gyllenhaal) awakens at 7:40 on a commuter train headed for Chicago. He is Captain Colter Stevens and he should be in Afghanistan as a military helicopter pilot. But he is sitting across from a woman who knows him as a teacher named Sean Fentress. He looks in a mirror and checks his wallet and comes to the conclusion that he is somehow inhabiting the body of Sean Fentress.
Precisely eight minutes after he wakes up, the train enters Chicago and a bomb explodes on the train, killing everyone on board. He is Captain Stevens again, strapped to a chair in a capsule and communicating through a video link with Captain Goodwin (Vera Farmiga) who tells him he is working on an experimental project called Beleaguered Castle. His mission is to find the bomb on the train and discover the identity of the bomber. But he cannot stop the bombing because you can’t change the past. Everyone on the train has died and always will.
He is sent back into Sean Fentress again and again, for eight minutes at a time, gathering information until he succeeds in finding out the name of the bomber, but he also wants to know the reason for the project and why he was chosen. And he is developing an affection for his travel companion, Christina Warren (Michelle Monaghan). The creator of the Source Code Project, Doctor Rutledge (Jeffrey Wright) and he do not have the same expectations. Because of Christina, he is invested in saving the lives of the passengers.
He learns that he died two months ago and when the job is finished, they will let him die permanently. He discovers that the bomber is a disturbed American named Derek Frost (Michael Arden) and the authorities pick him up. Despite his promises, Rutledge orders Stevens’s memory erased and stored so he can be used again, but Stevens convinces Goodwin to let him defuse the bomb, which he does. When he kisses Christina, he finds that his mind remains in Fentress’s body and he is in an alternate universe.
The film was directed by Duncan Jones and written by Ben Ripley. It was largely filmed in Montreal, and Montreal comic Russell Peters is in the film. Jake Gyllenhaal wore earbuds into which the director played music suddenly to help the actor look confused. The film received mostly positive reviews from critics. Colter’s father, on the phone, is the voice of Scott Bakula. He says, “Oh boy!” just as Bakula did on the TV series Quantum Leap. The pilot episode of that series had the same plot as Source Code. The same plot was also used in an Outer Limits episode called Black Box, starring Ron Perlman. Beleaguered Castle is a variation on the game of Solitaire.