Anyone who saw Duncan Jones' debut film, Moon, is in for a treat because Source Code is a solid follow-up. A sci-fi thriller in exactly the same mode, Source Code is a tightly plotted movie. Like Moon, Source Code revolves around conspiracy theories, altered states of being and false identities.

At the center of the story is Colter Stevens (Jake Gyllenhaal), a U.S. Army copter pilot who has crashed in Afghanistan. When he regains consciousness, he finds himself in civilian clothes aboard a commuter train on its way to Chicago. (To Chicagoans: if the train feels rather familiar, that's because it's a Metra that has been renamed the Chicago Commuter Railway.) The train is running slightly late. But that's not the worst of it: Colter Stevens appears to be in someone else's body. Eight minutes after this interesting opener, a catastrophic event throws Colter into yet another, even more bizarre situation.

At this point it becomes clear that the central theme of the movie is altered reality. The train and its occupants are on a countdown to a crisis that has to be averted. The only way to accomplish this is through bending the laws of time and space. Stevens is literally locked into a memory retrieval program that enables him to reside in the consciousness of another person for approximately eight minutes. Theoretically, that should be enough time for him to stop a disaster from occurring. If he can't, then he repeats those same eight minutes, though there are a finite number of times he will be able to do this.

Comparisons with Groundhog Day, Inception and Total Recall are not wide of the mark. Source Code has a sense of humor, some surprisingly great human drama, and a Philip K. Dick story ("The Adjustment Team") as a background. I'm not sure that there has been another writer whose work has been so deeply and so completely assimilated by Hollywood, and with good reason. Few writers had the gift of seeing the future of humanity, not as an exploration of space, but as an exploration of human consciousness, the way PKD did. That's why his stories lend themselves so readily to crafty thrillers like Source Code that end up becoming a perfect, even elegant blend of sci-fi and taut, Hitchcockian suspense.

Jones skillfully crafts his mystery piece by piece, building up a narrative tension that actually relies on parceling out information at key plot points as opposed to withholding all of it until the last minute. Gyllenhaal makes you forget all about Prince of Persia as he proves once again that he is one of the few actors who is as talented as he is good-looking. For pure summer entertainment, it doesn't get much better than this.