Weird science: Source Code a mind-bending ride

Source Code is an ingenious thriller that comes billed as science fiction, although its science is preposterous. Does that matter, as long as everyone treats it with the greatest urgency? After all, space travel beyond the solar system is preposterous, and we couldn't do without Star Trek. The "science" in this case is used to prop up an appealing story of a man who tries to change the past.

His name is Colter Stevens (Jake Gyllenhaal). That he is sure of. That's why it's strange when he finds himself on a Chicago commuter train talking to Christina Warren (Michelle Monaghan), a woman he's never met. It's even stranger when he goes into the toilet and sees a face in the mirror that doesn't belong to him.

How can this be? We are far from sure in the early scenes, which embed us in his confusion. Because some of the pleasure comes from unwinding the mystery, I'd advise you to stop reading now – unless the helpful TV ads have already hinted at the secret.

Spoilers ahead. Colter gains consciousness to find himself (as himself) in a secret Army lab talking to a scientist named Goodman (Vera Farmiga). He gradually understands that the commuter train was destroyed by a terrorist bomb, and that the brain of one of the victims was harvested for memories of the last eight minutes before the explosion. That's a first cousin to the old theory that a killer's image remains imprinted on his victim's retinas. Full review.