Michael Mann's first theatrical feature (in the United States, anyhow), Thief, has something of a reputation for being the Mann film that Mann fanciers haven't quite gotten around to seeing even though they know that they ought to, because it's supposed to be really good. Which, if it isn't true that it's really good, that's only because "really good" undersells it something fierce. Thief isn't just good, it's freaking brilliant; the best of all Mann's films or else I'll eat my hat (as of this writing, I've seen seven of his twelve features, and thus am taking a little bit out of turn) - and not just the best film of its director's career, but one of the best American films of the whole of the 1980s. It is a film with very few obvious flaws, "very few" becoming "practically none" if we consider the original theatrical cut instead of the dubiously-advised director's cut that is the only way to see it on DVD; and the immense strengths of the film would be more than enough to outweigh far greater problems than it displays.

While The Jericho Mile proved that Mann was well able to make a motion picture, Thief found him stepping up to the plate to make nothing less than a piece of right proper art, as boldly declared in the film's opening moments. It starts with a lengthy, dialogue-free sequence in which we watch as a team of thieves breaks into a bank vault to abscond with a handful of diamonds. It's always a bit thrilling to see an American film with the bravery to toss ten full minutes of wordless action, more so when those ten minutes come right at the start; and when the filmmaker in question is a newbie making his very first big-budget work, it moves from "thrilling" to "revelatory", especially given that Mann isn't just filming a group of men pulling off a heist. This sequence - like all the heist sequences in Thief - is marked by documentary-style precision about the actions being performed (thanks to a genuine gem thief who acted as consultant on the film and played a policeman), although it's hard to say that the film feels like a documentary at all: with all the sparks and molten metal and close-ups of mechanical objects and the like, the scene attains a poetic abstraction that somehow nestles quite comfortably next to its textbook-specific depiction of how to rob a bank. I'm not sure how a film can simultaneously feel that physical and realistic, and that confoundedly poetic, and that is why I know that Thief is a masterpiece.

As we'll learn eventually, the leader of this band of thieves is Frank (James Caan), who when we first meet him has wild, puffy '80s hair and a big pair of goggles, looking rather like the lead singer for The Buggles. Frank has a woman in his life, Jessie (Tuesday Weld), who isn't quite his wife because he wants to have a good life ready for her before they get married; it would seem in fact that getting his slice of Americana has become the overriding obsession of his life, so that when an old mobster named Leo (Robert Prosky, in his feature debut) offers him a big payday for designing and executing an unusually large robbery, Frank gulps down his natural disinclination to have anything to do with the mob, and takes the job. He carries it off with his customary brilliant planning and skill, but things start to go a bit corkscrew shaped when he and Leo have their post-heist powwow, and Frank learns, as he kind of already knew, that you don't just dabble with the Chicago mob and waltz away.

The primary conflict in Thief isn't, however, between Frank and Leo (it doesn't even come up as a conflict until near the end), but between Frank and the life he leads; it is a film about how a low-rent hoodlum wants very badly to be something, anything other than a low-rent hoodlum, except that he's, unfortunately, extremely good at it. Most of the film isn't really about anything even resembling a traditional narrative, but simple an exposΓ© of the life Frank leads, and how it makes him feel. Caan therefore has a lot to carry on his back, and he triumphs in what is certainly the best performance of his career - yes, better by far even than his iconic turn as the hotheaded Sonny Corleone in The Godfather. To watch him subtly demonstrate all of Frank's self-doubt, self-delusion, and fear is to see acting at its most perfect.

In his preceding film, Mann had a great central performance that he allowed to be the whole of the movie; not so in Thief. Here, the celebrated stylistic bravado that would become his calling card is on full, glorious display, and the manner in which he films Frank's spiral into the dark side is every bit as thrilling as Caan's performance. Thief is, above all things, an Impressionist film, depicting Chicago circa 1980 as a landscape of emotions and moods, and hardly as a recognisable city at all. Yet there is nothing in the film that is invented or changed. It's only the particular subjects that Mann and cinematographer Donald Thorin (whoever he is, this - his first film - argues strongly for his talents) choose to depict that seem strange and unusual. It would not be right to say that Thief suggests a dream-scape, but it nevertheless feels slightly unreal, showing a perception of a place rather than the place itself.

Adding to this effect is a Tangerine Dream score that has at times been much-lamented (it was Razzie-nominated!), but has aged well; or rather, it has aged poorly in a way that makes it about something other than just being a score. The music could never have been written at any point other than the early '80s, but it's strange and otherworldly enough that even as it marks the film intractably as a product of a certain time, it also takes the film out of time completely. It adds - dare I say it - a surrealist veneer to the movie's sound that meshes well with the impressionistic visuals.

The film is nigh-unto flawless, I said; and that flaw, unfortunately, takes place in the final moments of the movie (in the director's cut), leaving a poor taste in the mouth at the end. At this point, Frank has lost almost everything, and what he's not lost yet has been threatened, and he takes his vengeance out on the man responsible with quick violence. Now, all throughout the film, moments of violence have been depicted in slow-motion, a rare example of that technique being used perfectly. Except in the final moments, the violence is sped up, and while the slow motion was done practically, in camera, the speeding-up has been achieved "artificially" - so not only does it contrast unsuccessfully with the rest of the film's aesthetic, it looks amateurish and fake. Essentially, the last scenes of Thief abruptly become a crime movie version of Benny Hill. This is a damned shame, and I cannot imagine what the hell Mann was thinking when he did this.

But that's hardly five minutes out of 124; and the rest of Thief is as assured and basically perfect as any first feature has ever been. I do not always agree with the contention that Mann is a particularly great artist of crime films and the way than men function on the fringes of nice society, but in this case, it's hard to imagine any filmmaker doing it better. This is a pulp scenario elevated to sublimity.