by Ryan Hill

Colter Stevens (Jake Gyllenhaal) wakes up on a train. He has no idea how he got there, what’s going on or who the woman (Michelle Monaghan) sitting across from him is. Then he sees his reflection in the window – not his face. He rushes to the bathroom to get a better look. Before he can think about what’s happening, the train explodes.

Stevens is suddenly thrust into some sort of metallic pod, where Colleen Goodwin (Vera Farmiga) appears on a video screen, explaining to him that he’s part of a program known as the Source Code, which is about to send him back eight minutes in time in the body of a stranger. His mission is to find and stop the bomber, who has aspirations of detonating a dirty bomb in the heart of downtown ­Chicago.

From there, “Source Code” is a race against time as Stevens repeatedly ventures back onto the train in search of clues that will lead him to the bomber. Each time he fails within his allotted eight minutes, the train blows up.

Duncan Jones, who also directed the sci-fi mindbender “Moon,” hits on some similar themes in “Source Code,” especially concerning the finite amount of time we have to live and what we would do if we knew the end was in sight. Would we kiss a loved one? Try to save someone, even if it was hopeless?

Also, just as in “Moon,” Jones doesn’t let the film get bogged down in the physics of its own science fiction. Instead, it’s left to the viewer to try and flesh out the “Quantum Leap”-type mechanics of the Source Code. Is it a parallel dimension? A computer program? Reality? Jones and screenwriter Ben Ripley know that those questions are better off pondered after the credits have rolled.

Gyllenhaal, free from the ridiculous special effects of “Prince of Persia: The Sands of Time,” has a chance to grow into the leading man role for which Hollywood has been grooming him. He may not be a full-blown action hero, but his classic looks and boyish voice give him a vulnerability most leading men have difficulty showing.

“Source Code” is a success because it knows exactly what it is: a self-contained science fiction thriller that isn’t weighed down by lofty expectations or ideas. By focusing on the tension and characters’ relationships with Stevens, especially as he learns the truth about why he’s in the Source Code, Jones has crafted an emotional, high-stakes thriller that is equal parts thought-provoking and exciting, and stands as the best film released so far in 2011.

Grade: 3.5/4 Stars