It's the obvious thing to say, but it can't be avoided: "Source Code" is the science-fiction thriller version of "Groundhog Day," and that turns out to be not a bad thing at all.
Crisply directed by Duncan Jones from a cleverly constructed Ben Ripley script, "Source Code" doesn't have protagonist Jake Gyllenhaal repeat the same day ad infinitum the way Bill Murray did; no, he has to relive a particular eight minutes over and over again. Not because he wants to but because, wouldn't you know it, large numbers of innocent lives are at stake.
With a twisty, mind-bending plot that frequently changes direction and occasionally overreaches, "Source Code" wouldn't work at all without a cast with the determination and ability to really sell its story. With Gyllenhaal, Michelle Monaghan, Vera Farmiga and Jeffrey Wright in the key roles, that's just what it has.
It's Gyllenhaal's character we encounter first as he wakes up groggy and haggard on a commuter train headed into Chicago after what looks to have been a troubled sleep. And that isn't the half of it.
This character thinks he's Army Capt. Colter Stevens, Afghan war veteran, but Christina Warren (Monaghan), the woman seated opposite him on the train, keeps calling him Sean. And when the captain looks into a mirror, it's not his own face he sees, but Sean's.
Making things even more confusing, after exactly eight minutes the train explodes and an even more disoriented Stevens inexplicably finds himself in a space capsule talking via video hookup to Capt. Colleen Goodwin (Farmiga), his military handler. Some confusion, she tells him, is perfectly normal, which is putting it mildly.
It is the conceit of "Source Code" that we find out what is going on at the same time Stevens does, and the explanation is so complicated that it's a good thing Dr. Rutledge, the man who finally provides the details, is played by as calm and persuasive an actor as Wright.
Roughly stated, it turns out that "source code" is the name for a mysterious process that allows Stevens to in effect go back in time to a kind of parallel universe and assume another person's identity for the last eight minutes of that man's life.
Stevens can't change the past, can't prevent that train explosion, but he can affect the future. His assignment during those eight minutes is to identity the bomber, an individual who simply must be stopped before he plants a bigger, deadlier bomb in Chicago itself.
It may sound like a version of hell for moviegoers to have those eight minutes on a train replayed over and over and over again, half a dozen times at least, but the film has come up with a surprising number of variations on that theme. Far from making "Source Code" dull, those repetitions add to the tension as we wonder what Stevens will do next and how that choice will play out.
It also helps that the film team has a feel for the genre. Duncan Jones' first film was the Sam Rockwell- Kevin Spacey "Moon," cinematographer Don Burgess shot both "Forrest Gump" and "Spider-Man," and while writer Ben Ripley, whose credits include the straight-to-video "Species III," stumbles in some areas, his sense of plot is undeniably strong.
"Source Code" is also fortunate in the actors it has for its quartet of key roles. Wright's quiet charisma is echoed by Farmiga, who brings formidable controlled energy to an essentially desk-bound role, but it is the people we see over and over again, Gyllenhaal and Monaghan, who make all the difference.
Committed to the project even before a director was selected, Gyllenhaal brings a sense of passionate belief and commitment to Stevens that "Source Code" could not succeed without. When you add in Monaghan's trademark vivacious presence, her ability to be fully alive in each and every one of those nominally repetitive moments, science-fiction romance is definitely in the air.