In "Blood Simple," a gothic tale of jealousy and bloodletting, two young filmmakers, director Joel Coen and his brother, producer Ethan (who cowrote), make a debut so brazenly confident they could hire Lee Iacocca as their pitchman: "If you can find a better-built, better-backed American movie, buy it." With an irresistible blend of meticulous construction and mordant humor, "Blood Simple" is the funniest comedy and the thrillingest thriller in what seems like an age.

Unlike most modern film noir, "Blood Simple" isn't an hommage to old movies, but to the books those movies were based on; it has the literacy of a Raymond Chandler novel, the freshness of a genre discovered for the first time. The title comes from Chandler -- "blood-simple" was his term for someone addled by the act of murder -- the spirit from James M. Cain. Julian Marty (Dan Hedaya), a grotesquely grim saloon owner, suspects his wife (Frances McDormand) of infidelity, so he hires Visser (M. Emmet Walsh), a detective and "Elks' Man of the Year" (according to his engraved cigarette lighter), to shadow her; sure enough, she's having an affair with one of Marty's employes, Ray (John Getz).

What follows is a classic carousel of death, detours and double-crosses; "Blood Simple" is made with dazzling economy, as each line and each shot (or often, different things within a single frame) prepare the action that follows. Everything in the movie suggests danger. Time after time, the Coens tease us with mayhem -- for example, a dying victim pulls a gun, only to have the hammer click on an empty chamber -- as a way of building the suspense for the times mayhem is unleashed. If suspense is a bomb that doesn't go off, then plenty of bombs don't go off in "Blood Simple."

And plenty do. "Blood Simple" swims (toward the end, literally) in a bucket of blood; but as with all the effects in the movie, you're always aware of the intention behind it. Indeed, that's the key to the pleasure of the movie -- like the young Orson Welles, the Coens are enthralled with the tricks of their art, the devices with which they set up thrills and jokes, and they invite the audience to join in. The spirit of the movie is that anything goes -- key moments, for example, are accompanied by a Balinese monkey chant (of all things) on the score -- but everything is calculated. The effect is a pleasurable tension between spontaneity and shrewdness. "Blood Simple" is like a Swiss watch with the back pried off, the wonderfully complementary levers and gears apparent to all.

The essence of the movie is that the characters alone aren't in on what's happening; "Blood Simple" is a movie about stupid people, but the stupidity has a context. These people are "blood-simple" and "greed-simple" and "lust-simple"; they're prisoners of their own obsessions, insulated from reality by desire. If they ever came out of themselves and talked to each other, the killing spree would grind to a halt -- the stuff of "Blood Simple" lies in the failure to communicate, a failure born of self-absorption. Immersed in paranoia (the kissing cousin of egomania), they suspect the worst of even those they love, and the worst occurs.

If the intention of every scene is clear, the image itself isn't; cinematographer Barry Sonnenfeld seems to have lit the movie with a 60-watt bulb. It's every bit as dim as its protagonists are dim-witted. The real triumph of "Blood Simple," though, is its visual density, the way every image functions on a multiplicity of levels. When Marty "has it out" with Ray, for example, the only light is provided by a bug zapper, which then crackles to punctuate an awkward silence. The zapper, in other words, is at once functional (as a natural source of light), humorous (a sort of heckling chorus to Marty's dour funk), and thematic (throughout, flies harry these characters, as if they were already carrion). What's astonishing about "Blood Simple" is that almost every shot has this kind of texture; instead of the usual formula of thrills alternated with comic relief, the movie weds jolts and jokes seamlessly. It's all of a piece.

Hitchcock is famous for saying actors should be treated like cattle, but he was able to get definitive performances from many of them, and Joel Coen seems to have the same kind of touch -- he doesn't seem that interested in the actors, but they're terrific nonetheless. McDormand has a kind of daft integrity; her monotone bespeaks the carelessness with which she goes from man to man, heedless of consequences. In one of the movie's visual jokes, her cleft chin reiterates Hedaya's. And Getz, with his perpetually puzzled expression and thick lips that recede of their own weight, nicely evokes Ray's dumb courage -- here's a man who's always out of his depth.

But the gems of "Blood Simple" are Hedaya and Walsh. His jaw locked up like the door of a mailbox, eyes glaring in an obsidian gaze, Hedaya has the aura of a penny-ante Mussolini. He's a textbook Type A, wound tight in some permanent, unknowable rage of which his cuckoldry is only the most recent element. Hedaya is always looking off into corners, trying to ferret out the enemies he's sure are there; and when he tries to pick up a woman at his bar, he appraises her like a used car, rolling his tongue out of his mouth as if he's licking his last stamp. You hate him, but when he's finally at the end of his rope, he wins your sympathy -- the pitiable flecks of his humanity show through.

Walsh's vast belly rises like Krakatau -- his bigness only emphasizes the pettiness of his spirit -- and his yellow leisure suit seems to ooze out of him. He's the personification of decay, muttering his drolly obscene lines with the warble of Roy Orbison and the lubricious cadences of Mae West. With his face like a crushed jelly doughnut, his expression sealed in contempt, he's utterly imperturbable -- when Hedaya threatens him, the screen fills with smoke rings blown by an off-screen Walsh -- because when you expect the sleaziest, you're never surprised.

Walsh's Visser is an odd spokesman to choose, but he's clearly the one closest to the Coens' hearts. "Blood Simple" is peopled with vivid losers, but it isn't interested in characters so much as things -- the camera loves to follow objects, whether it be a brace of fish rotting on Marty's desk, Visser's cigarette lighter, the high-topped basketball sneakers of a bartender as he struts across the floor, a thrumming ceiling fan or a newspaper clattering against a screen door. It's a materialist's universe. When Visser opens the movie by contrasting the Communist ideal with Texas -- "Down here you're on your own" -- he's setting the stage for a movie that, for all its blithe entertainment, harbors deep inside it a critique of individualistic materialism gone amok. Blood Simple, opening today at area theaters, is rated R and contains violence and profanity.