What is the audience for this movie? It is carrying on in its own lifetime a style of film that was dead before it was born. Are teenage moviegoers familiar with movies like "The Maltese Falcon"? Do they know who Humphrey Bogart was? Maybe it doesn't matter. They're generally familiar with b&w classics on cable, and will understand the strategy: The students inhabit personal styles from an earlier time.

This mixing of styles and ages has been done before. Alan Parker's "Bugsy Malone" (1976) was a 1930s gangster movie cast with pre-teen kids (including Jodie Foster). Once you accepted the idea, it worked, and so does "Brick." The crucial decision by writer-director Rian Johnson is to play it straight; this isn't a put-on, and the characters don't act as if they think their behavior is funny.

The movie opens in James Ellroy territory, with the hero Brendan (Joseph Gordon-Levitt) finding the dead body of his onetime girlfriend in a drainage ditch. From the mouth of a tunnel comes the sound, perhaps, of her murderer escaping. The victim is Emily (Emilie de Ravin), who called him earlier for help; from a lonely phone booth (itself a relic of pre-cellular movies) he sees her being taken past in a car, possibly a captive.

Brendan turns into a classic 1930s gumshoe, tracing her movements back through a high school drug ring and ignoring threats from a high school principal who tries to pull him off the case (this is the role police captains filled in old private eye movies). True to the genre that inspired it, the movie has tough and dippy dames, an eccentric crime kingpin, some would-be toughs who can be slapped around like Elisha Cook Jr. in "The Maltese Falcon," and an enigmatic know-it-all. This last character was, in the old days, an informer, bookie or newspaper reporter often found in the shadows of a bar; in "Brick," he apparently exists permanently while sitting against a back wall of the high school, from which vantage point he sees and knows, or guesses, everything.

Does the movie work on its own terms as a crime story? Yes, in the sense that the classic Hollywood noirs worked: The story is never clear while it unfolds, but it provides a rich source of dialogue, behavior and incidents. Then, at the end, if it doesn't all hold water, who cares as long as all of the characters think it does? "The Big Sleep" is famous for the loophole of a killer who is already dead when he commits his crime. At the Madison Film Festival last weekend, I saw "Laura" again, and was reminded it is entirely a movie about atmosphere, dialogue and acting styles, in which the very realities of murder are arbitrary. It makes no difference who committed the central killing; what's important is that everyone acts as if it does.