As a general rule, most time travel tales are ones that we would count ourselves lucky not to get wrapped up in. Paradoxes, unforeseen consequences, and general risk of injury are things to be avoided at all costs - but passing up the chance to solve a mystery is one few can resist.
While Duncan Jones' Source Code may not be as revered as the director's other work, we can't help but appreciate the attempts made by the story. Mainly, to bring sci-fi time travel together with a suspenseful detective story. The role of detective falls to 'Colter Stevens' (Jake Gyllenhaal), able to re-live the last minutes of one terrorist attack's victim. His task is simple: repeat the process until he's gained enough information to discover who was behind the attack.
The film may stray from the basic premise, but it's strong enough to deliver not only an entertaining - and easy to follow - thriller, but bring something new to the notion of a 'time loop.'