I’ll categorise Source Code as “sci-fi” rather than “thriller” or “action and adventure” purely because it seems to fit there better than any.  The scenario is so improbable it could only at best be viewed as such, but if you wanted to do the Hollywood thing of describing in terms of other movies, you would probably have Groundhog Day meets Unthinkable, or any other of the many movies featuring a hidden bomb.

But that’s not the whole story.  Nope, not at all. Our hero, Captain Colter Stevens, who looks remarkably like Jake Gyllenhaal, is a helicopter pilot doing service in Afghanistan.  He first wakes up on a commuter train en route for Chicago,  in the body of a teacher he does not know.  The train blows into spectacular smithereens after 8 minutes.  Colter is then jolted awake up in what appears to be a poorly-equipped survival pod with a screen giving him access to Captain Colleen Goodwin in the shapely form of Vera Farmiga.  You are intrigued!  So what is going on? you say to yourself.

Well we do eventually get some back story, though it basically seems a lot of hokey.  Colter has been at codename “Beleaguered Castle” for two months.  His mission, should he have a choice whether to accept it, is to go back repeatedly into the source code of the last 8 minutes memory of said teacher to find the bomb, who planted it, and thereby stop a bigger dirty bomb being planted in Chicago by the same bomber.  Hope you’re keeping up, there will be a short test later (said with tongue in cheek.)

In the course of these adventures he does discover a few more details, such as that he is barely alive following a crash in Afghanistan, but his brain is functioning, therefore it’s a lot of scientific mumbo-jumbo spouted by Dr Rutledge (a very uncomfortable Jeffrey Wright) to keep him alive and focusing on the task in hand.  Secondly, that he can actually alter the course of history in Source Code.  And finally that he is rather partial to his travelling companion, Christina Warren (Michelle Monaghan), since any Hollywood movie has to have some form of love interest.

Such is the basis of the plot, though having established the mise-en-scène, director Duncan Jones (who also directed Moon) delivers with economy but struggles to fill the allotted 93 minutes with the momentum such a concept truly deserves – despite being on the busy side for most of the space between opening and closing titles.   Instead, a great idea fizzles out in the second half, and a denouement which reveals the state in which Colter actually returned from Afghanistan, and that he can and does use Source Code to rewrite history and save lives, seems more of a damp squib than it should.

Jones and scriptwriter Ben Ripley could, had they so desired, have spread the mystery out much longer found ways to expand interest in the characters and situation.  The audience is encouraged to wonder what they would do in the same circumstances, but not enough is done to make you care about them.

A shame, since I want so much to give this movie a more positive rating.  There are plenty of positives, not least a fine cast, a good early build-up of tension and well executed special effects.  Maybe someday there will be a remake which re-imagines the plot and tacks on a few more twists and turns, in the best (or in some cases worst) Hollywood traditions?