Source Code is surprising on two fronts. Firstly, that an action film directed by Duncan Jones, who famously crafted the quiet and contemplative Moon, and starring pretty Jake Gyllenhall could turn out to be a serious contender for the best film of the summer. The second major surprise here is that even the most devoted Phillip K Dick fan may well look for the author’s name on the credits somewhere, only to discover that this is a wholly original piece of work.

The intelligent writing of the film even encompasses some theoretical elements of quantum physics, asking mind-blowing questions about the nature of the universe, parallel worlds and even indirectly touches on the multiverse concept. This is a toweringly cerebral piece of science fiction which Dick would have been proud of.

The action opens on a commuter train, where our hero Colter awakes, seemingly in the body of another man. Without giving too much away, as it is extremely tricky to avoid spoilers, it is explained that he is able to relive the same 8 minutes through this particular man’s eyes, in order to prevent an act of terrorism in the real world. What could have turned out to be a poor man’s Inception, laced with elements of Groundhog Day thankfully avoids that trap, with the subtle differences to the same scenes inviting, without insisting on, a certain level of perception from the audience.

The blend of action, suspense and humour is just right as Colter gets to grips with his mission, preventing the film from getting boring, which is quite an achievement when dealing with only 8 minutes of basic structure.

The casting of Source Code is spot on. Gyllenhall is in almost every scene, and believably plays the hero. He takes the audience through anger, elation, sadness and steely resolve as the determined but confused Colter in the film’s short run time. His absorbing central performance is helped by a subtle turn by Michelle Monaghan, whose character serves as Colter’s love interest of sorts. Vera Farmiga’s mission controller serves as an excellent hub for the film’s complex plot, and again she plays this role with just the right mix of military efficiency and warm humanity. The only bum note on this front is a shocker – Jeffrey Wright, such a reliable performer usually, plays the boss of Farmiga, but completely overacts many of his scenes, which result in his character sticking out like a sore thumb amongst the cast as he chomps relentlessly through more and more scenery. It is a bizarre turn in which he growls his lines with such ferocity that it comes close to disrupting some scenes which are very important to the narrative.

The action sequences are exciting, with the ever-ticking threat of that 8 minute time limit proving a great antagonist, the audience may find themselves checking their own watches as obsessively as Colter does. The excitement when he makes progress, and disappointment when an obstacle presents itself are palpable, all helped by a throbbing score.

Unfortunately, the ending to the film does stumble, seeming to end two or three times, and rather than finish with a bang it has to be said that the film just quietly shuffles off screen for the credits to roll. It is somewhat interpretive, much like Inception’s ambiguous climax, but for the audience to be able to really form their own conclusions perhaps less should have been made explicit in the final five minutes.

With this powerful effort, Duncan Jones has announced himself as the science fiction director to watch at the moment, having produced an action film with genuine intelligence and poignancy behind it here. The great cast, gripping story and explosive action is a must-see for all Sci-Fi fans, and it is refreshing to see a truly original film released in what looks set to be the year of 3D sequels.