We appear to be in a boom cycle for science fiction-tinged love stories with a nifty conceptual hook that gets buried by the filmmakers' desire to entertain adults; first The Adjustment Bureau, now Source Code - the latter of these being altogether a stronger, tighter work, though they share a similar weirdness about apparently believing themselves to be intellectually probing when they are in fact largely ephemeral. Which sounds like a complaint, but it isn't: when ephemera is as dazzling and fun as this, it's rewarding all on its own, thanks so much, no apology or mental twisting necessary to make it "good".

The over-eager-to-explain ad campaign has somewhat ruined a real corker of an opening: the credits over shots of a commuter train headed through the Chicago suburbs, followed by a passenger on that train, a confused man who insists that he's named USAF Capt. Colter Stevens (Jake Gyllenhaal), even though the woman sitting across from him (Michelle Monaghan) insists on calling him "Sean". He spends eight minutes in a state of despair, when the train explodes.

He then ends up in a metal capsule, with a different woman (Vera Farmiga), talking to him through a video monitor. She recognises him as Stevens, but refuses to explain what happened, why this isn't Aghanistan, or the identity the lurking man with a crutch (Jeffrey Wright) behind her. Eventually, the panicked Stevens finds out that thanks to some blah blah technobabble he is able to inserted into the last eight minutes of life of a man who died that morning in a terrorist attack. Stevens's mission is to find out who was responsible, before a similar attack can wipe out the city of Chicago with a dirty bomb.

It's off the races after that, and I would not for money reveal any more of the plot, except to say that even as Stevens investigates the explosion, he also tries to figure out what happened to get him involved in this most peculiar military operation, code-named "Source Code" after the technical description of the dead Sean Fentress's mental pattern, miraculously saved to a computer hard-drive. The film does triple duty: as an espionage thriller, a mindfuck movie, and a good old-fashioned story of the human spirit, as Stevens begins to fall in love with his seatmate & explores the metaphysical ramifications of his experience inside the source code. That said, the film's metaphysics are somewhat undernourished, about on par with its defiantly hokey approach to biochemistry, and any hopes that second-time director Duncan Jones was going to follow his exquisite debut feature Moon with another incisive, difficult study of the human mind in a genre context aren't borne out by the finished product. Source Code is a much slicker, more studio project, "difficult" only according to the standards by which the exposition-laden Inception somehow got tagged in the media as an inscrutable puzzle. On the other hand, Moon is so damn brilliant that even if Jones never makes anything that good again, it leaves plenty of room for movies that are, by themselves, tremendously accomplished works of idea-driven storytelling; and that is the niche into which Source Code falls.

Starting with its screenplay by Ben Ripley - a great big world away from Species III, and even farther from Species: The Awakening - the film is the very model of scrupulous, careful storytelling, where every chunk of information gets some pay-off later, where the sometimes wildly loopy plot contortions are always neatly built upon the basis of what comes before. On top of its other guises, Source Code is also a mystery: by the the end, the questions of What is the Source Code project? and How did Colter Stevens get involved? are far more important than the terrorist plot, so inessential to the movie that it eventually gets resolved offscreen; and as Stevens muscles his way through each layer of puzzles the movie throws at him, the audience is always in possession of exactly the information he has at that moment in time, never a step behind, never a step ahead (though since we know we're watching a movie, certain things can be fairly easily guessed). Even the film's big twist comes at a point where it makes dramatic sense, miles before the ending, so it has a chance to sink in and we can actually appreciate the ramifications of the twist, rather than just being sucker-punched. It's a methodical, intellectually satisfying way of telling a story, and I'm probably making the film sound like kind of a drag, which it completely isn't.

On the contrary, momentum is one of the film's best attributes. There's a lot about the film that doesn't hold up: where did Sean Fentress's brainwaves come from, if he vaporised in an explosion? how can Stevens experience things that were nowhere within Fentress's field of vision (right there, there's that metaphysical thing that the movie sort of stumbles with, though it's obviously proud of it, foregrounding the metaphysics in an ending that works even though it's awfully precious)? And so forth. You don't notice these things during the movie. At least, I didn't. For the filmmakers out the central concept with the cleanest exposition possible, ask us to trust that it will be worth it if we buy into that concept, and whisk us away on a mad dash through plot and twists. Winding up, credits and all, at just a touch over 90 minutes, Source Code is a crazy-ass dense and fast movie, the exact opposite of the stately, introspective Moon; it snaps through some of the most crisply, brightly edited scenes in a thriller in months, almost every scene adds something new for us to chew on, and the whole thing is over almost as quickly as it begins. It's a giddy damn delight, or so says the big goofy smile I was wearing when the lights came up.

Jones and his excellent crew, including crackerjack editor Paul Hirsch (whose career has swung wildly from Star Wars to Date Movie, with all kinds of stops in-between), cinematographer Don Burgess, and a phenomenal sound team led by Tom Bellfort, do such an amazing job of keeping the film sizzling along, finding an infinite number of ways to keep the flow between the high-energy scenes on the train and the slow-boil paranoia scenes in the Source Code mission room, that one could almost overlook the human element; certainly it's fairly boilerplate stuff about the power of free will and spirituality and all, but told with a fair degree of conviction, and well-acted, with Monaghan on her best behavior proving to be an outstanding romantic lead for Gyllenhaal; though the movie is rather stolen by Farmiga and Wright in two marvelous supporting performances, hers a subtle masterclass in conflicting emotions, the desire to be a decent, sympathetic person butting against the need to get the job done and be all military; his a grand, hammy descent into the robust quirks of a jovial mad scientist.

Meanwhile, for all that the ending is a bit silly and contrived, it's awfully generous and even sentimental, a sweet little metaphor for the soul overcoming all obstacles. At any rate, it is unabashedly humanist in a way that's earned, not forced onto the film; underneath all the steel and explosions and Ohmigod there's a bomber! trappings, it's a story about people fighting and struggling to survive and love, and though it's told in a somewhat corny way, it's that, and not the warped storytelling, that makes Source Code a film worth keeping.