On the way into Rian Johnson's high-school thriller, Brick, you can pick up a handy glossary of the film's language: you'll need it. We're not talking about standard US teen-speak: I don't believe I heard a solitary "dude" or "as if". Instead, it's "scrape", "bulls", "gum", "sprang" (as in, "His gat sprang from Tugger's gang"). Brick's weird, hermetic universe is defined entirely by language - a language partly culled from, partly contrived to evoke, the hard-boiled codes of Dashiell Hammett, Mickey Spillane and Damon Runyon.
Johnson's film isn't easy to follow, as it's scripted almost entirely in Brick-speak - a mixture of the above lexicon and a more transparent line in Forties-flavoured backchat. Even the simplest exchange leaves you scratching your head. For example: "Coffee and pie." - "Coffee and pie, oh my?" - "And you didn't hear it from me." It's only in the following scene that we learn that Coffee and Pie Oh My is the name of a local diner, where a gang of doped-up slackers hang out - which explains why hero Brendan (Joseph Gordon-Levitt) calls one of them "a pie-house rat". Stick with Brick and it all starts to slot into place.
Not that things are entirely clear to Brendan either. Taking a desperate phone call from his vanished girlfriend Emily (Emilie de Ravin), even he has to crack the code she's using: "brick", "lug", "pin". Like The Big Sleep rewritten by a cryptic crossword setter, Johnson's tantalising debut is a wayward and welcome anomaly, rather like last year's sci-fi time-bender Primer - one of those American independent films that challenge you to work your brain. Fortunately, a recognisable template beneath Brick helps us navigate the maze. This is a classic find-the-lady film noir, inspired by Hammett, Chandler and James M Cain, but peopled by high-school students. Lovelorn for Emily, Brendan follows the clues into a small-town undergrowth as murky as those of David Lynch's Lumberton or Twin Peaks. Emily, we know from the start, will wind up dead, but Brendan's mission is nevertheless to redeem her - her scuffed shoes and blue nail varnish mark her out as a fallen angel - and wrest her from the underworld. The two narrative models here are Orpheus and Eurydice, and "Who killed Laura Palmer?".
Brick might almost be parodying the fact that few American high school movies are remotely about high school: usually, the enclosed space of school is a model of the damaged, bruising nature of the adult world outside. In any case, no one in these films ever seems to spend much time in class. Johnson makes eerie play on this when Brendan is pursued by a thug around the deserted school perimeter: as they pass windows, we hear cheerleader practice and a piano lesson. But Brick's world is quite separate from real-life schooling, or even real-life delinquency.
It's a world in which teenagers act out Forties film roles: shamuses, femmes fatales, Moose Malloy lunks, elusive crime czars. We only ever meet an adult authority figure in a face-off between Brendan and the school's Assistant Vice Principal (Richard Roundtree, of Shaft fame), a scene that's really about the lone gumshoe being hauled in by the sceptical cop. "Write me up or suspend me," Brendan taunts him with Bogartian sangfroid. "Otherwise I'll see you at the parent conference."
The dark stuff in Brick is more than just play-acting: people really get beaten, killed, sold lethal drugs. But the film is so unsettling because of its absurd disjunction between extremity and the teenage everyday. A mysterious card hints at an entrée into decadent hell, as in Eyes Wide Shut. In fact, it's just a ticket to a rich girl's party in her parents' house. Even the dark bunker of "The Pin" (Lukas Haas), a local drug baron slightly older - and considerably creepier - than the other characters, turns out to be situated in the basement of his mother's suburban house: Mom cheerily offers apple juice in the kitchen, in a chicken-shaped jug.
Gordon-Levitt (last seen in Gregg Araki's Mysterious Skin) plays Brendan as a quietly noble Philip Marlowe figure: a shabby cynic with a big heart, nerdy and shambling of demeanour, but with an expectedly dazzling right hook. He's so improbably tough, in fact, that I found myself wondering whether Brendan isn't the idealised projection of his cerebral friend and aide, the library-dwelling, Rubik's Cube-twisting Brain (Matt O'Leary), who may even conceivably be the secret "author" behind this fevered pot boiler. Just a thought. Brick is the kind of film - like the showier and arguably less intelligent Donnie Darko - that tips you towards this kind of speculation.
Johnson gives us more than a fanciful premise: he has a strange stylistic touch too, picking up on troubling details (close-ups of a bracelet, shoes, a fag end) or pulling unsettling sound tricks (uncanny squelches as people walk on grass, a thunderous showdown heard only as muffled sound through the ceiling). Brick also has an extremely strange score, including screeching brass, mentholated electric piano, and a zither song on the radio, presumably to set you thinking of The Third Man. On a second viewing, Brick may possibly turn out less complex than it seems: perhaps the opaque language is a dazzling screen that blinds you to what's conventional about the film. You certainly want to see it again, though - but brush up on your glossary first.