Against closure.

LONG, repetitive, and deliberately inconclusive, David Fincher's Zodiac is the best movie of 2007 so far, and a better piece of filmmaking than anything nominated for Best Picture in the year just past. Superficially more conventional than his brilliant 1990s provocations, Seven and Fight Club, Fincher's latest film is actually another exercise in subversion, in which the familiar rhythms of two crowd-pleasing genres--the serial-killer film and the police procedural--are faithfully recreated and then allowed to dissipate gradually into a miasma of missed connections, lost opportunities, and ambiguity. It's a craftsman's calculated rebuke to his audience's expectations: a thriller where the action is frontloaded and the payoff never really shows up.

Fincher's ostensible subject is the Zodiac killer's reign of terror in the late-Sixties Bay Area, which either lasted ten months or well into the Seventies, depending on whether you believe that all the unsolved murders the psychopath claimed credit for were actually his doing. But Zodiac is mainly concerned with what happened after the killing stopped and the trail went cold: The only on-screen murders take place near the beginning of the movie, and in the two hours of painstaking investigation that follow there are none of the damsel-in-distress, race-against-the-clock contrivances that even highbrow thrillers employ to jolt the audience awake. Nor, apart from one unnerving interview, does the killer's personality or psychology ever take center stage: The detectives don't use astrological tables to predict where he'll strike next, or parse the cryptograms he mailed to the San Francisco Chronicle for hints of some childhood trauma or buried psychosexual compulsion. The Zodiac's motives and personality, like his identity, remain persistently hidden--the unknowable unknown at the heart of the plot, the dark matter that holds the movie's universe together.

Three men, in particular, are pulled into the case, like metal filings swallowed by a magnetic field--Robert Downey Jr. as Paul Avery, the hard-living Chronicle reporter who covered the murders; Mark Ruffalo as David Toschi, the San Francisco detective assigned to the case; and Jake Gyllenhaal as Robert Graysmith, the Chronicle cartoonist who became obsessed with the unsolved mystery and launched his own, layman's investigation even as the cops were giving up. From their three overlapping stories, the film opens outward, revealing a sprawling canvas of the lives the killer touched--Ruffalo's partner and his superiors, the cops in the suburban towns where the killer also struck, Avery's editors, Graysmith's wife and children, and then a host of others, witnesses and victims and sources and suspects. Fincher has assembled an astonishing collection of character actors to bring his tapestry to life--Chloe Sevigny and Brian Cox, Anthony Edwards and Elias Koteas, Dermot Mulroney and Philip Baker Hall--and there's purpose in every casting decision. By using a James LeGros or an Adam Goldberg or a Clea DuVall--all actors you immediately recognize, but can't quite place--in minor roles, Fincher adds weight even to the walk-on parts, implying that his expansive film only begins to reckon with how far the ripples from the killings spread.

The first two-thirds of the movie belongs to Avery and Toschi, with Gyllenhaal's Graysmith--an eager-beaver Eagle Scout, nicknamed "Retard" by his jaded colleagues at the Chronicle--lurking in the background. Then Zodiac leaps forward in time and doubles back on itself, with an increasingly obsessive Graysmith revisiting territory we've already seen the cops cover, ostensibly to research a book on the case but really in the hope of solving it. His faith in closure makes him a vehicle for the audience's expectations--long after everyone else has given up, he's still holding out for the truth, and we're there rooting him on, hoping for our money's worth, for the moment of catharsis and resolution that every mystery story promises.

Throughout, though, it's clear that Zodiac has something else in mind. Graysmith isn't Clarice Starling from Silence of the Lambs, battling sexists and psychopaths to get her man. As Gyllenhaal plays him, he's a nice enough guy but also an obsessive-compulsive weirdo, who wrecks his marriage and risks his life for a chance to look a killer in the eyes. Avery, the journalist, is a self-destructive narcissist who makes himself the story and throws up roadblocks for the cops; Toschi is a competent detective trapped in a dysfunctional bureaucracy, where turf wars, primitive technology, and human fallibility consistently trump good police work. Nor is the killer himself invested with anything like the malignant allure of a Hannibal Lecter, or the crazed Thomist who cut a swath through Fincher's Seven. He is a nullity, when we have no idea whodunit; and, even once we suspect we do, he remains an irruption of evil that's defined only by what he negates--sanity, morality, and life itself.

There are contrasts drawn between movieland and reality. Acharacter notes in passing that Ruffalo's Toschi was the basis for Steve McQueen's Bullitt, and near the midpoint of the film, just as the police inquiry is running out of steam, several of the characters show up at the San Francisco premiere of Dirty Harry to watch Clint Eastwood's hero cop chase, and catch, the Zodiac-inspired "Scorpio." Late in Graysmith's investigation, Fincher drops him into a perfect thriller set-piece, leaving him alone with a creepy suspect in a creaking basement--and then exposes the whole thing as a red herring. The movies are just the movies, Zodiac insists; the Zodiac killer was real life.

In the end, of course, Zodiac is a movie too, and Fincher's reality-encompassing ambitions are a weakness as well as a strength. His film might have been better either shorter or longer than its present length--either as a tighter story, with fewer subplots and blind alleys, or as a still-more-epic picture, with more elbow room for characters who are shortchanged in the current cut.

But Zodiac is still a remarkable achievement, a rare film that manages to tell a complicated story without condescending, and a sensational story without pandering. It's a gripping entertainment shot through with existential dread, which sounds like a contradiction but turns out, in Fincher's hands, to be the best way to look at not only the hunt for the Zodiac killer, but the human condition itself.