A man (Gyllenhaal) wakes up on a train. The unknown girl opposite (Monaghan) knows who he is, but calls him by a different name. As he tries to figure out what's going on, the train is destroyed, blown up by a terrorist bomb. The man finds himself inside a pod, being addressed by an Air Force officer (Farmiga): turns out he is former helicopter pilot Colter Stevens, and is embedded in a military project which allows a user to experience an eight-minute chunk of another's life. His mission - and he doesn't have much choice as to whether to accept it - is to find out who on the train is responsible, and stop them, not only from blowing it up, but from executing the larger, nastier terrorist attack they have planned as a follow-up. Stevens will be repeating the same eight-minute chunk, with variations, until the case is solved. He also discovers the nasty truth about the project: that he was all but killed in a Afghani 'copter crash, leaving his body on life support, and the pod is a construct of his mind to handle the situation.
As the list below shows, this kind of things has been done before, and this is particularly close to Deja Vu in story. The script also occupies a tricky, and ultimately unsatisfying, middle-ground, neither offering a convincing explanation for the time-travel and its mechancis, nor failing to bother with one - either would likely have been preferable. That particularly weakens things at the end, where the previous rules appear to be discarded, for the sake of a convenient loophole through which the film saunters, in order to fulfill its date with Hollywood convention. However, if you don't peer too close, this still delivers passable entertainment, with a set of decent performances. Those are led by Gyllenhaal, who makes an engaging hero, uncovering what's going on, as the audience does: there's nothing hidden from us which isn't hidden from him. That helps bring the audience in, and distract them from the holes in the plot. Jones - whom I didn't realize was David Bowie's son - has made something here which is a little smarter than the average Hollywood popcorn flick. However, it's definitely not as clever as it thinks it is.