ALAN MOORE and Dave Gibbon's Watchmen, written in the mid-1980s, is a dreary affair from first panel to last. It churns out its grimy vision of Manhattan with, in addition to signature reds and blacks, pukey greens, stale yellows, erotic pinks, all vivid and sickening. Its titular masked avengers confront palpable moral contamination and shrink from harrowing geopolitical apocalypse, all while wrestling their own deeply dysfunctional personalities. Their world is sunken in darkness and saturated with blood. The faces of dying innocents stare back at you through the panels as you read, and sometimes you pause, unable to go on.

Not so with Zack Snyder’s loud, shiny movie, propagandized for so long and with such laughable overstatement (“from the visionary director of 300!”) that it almost had to be a bloated failure. But it turns out Snyder’s Watchmen (Warner Brothers Pictures) is more of a fanboy’s dream, carefully crafted and painstakingly detailed. It follows its source material with religious devotion, unfolding like tightly wound, perfectly polished clockwork. And following in the novel’s footsteps, it really makes an effort to hurt you. It tries, and tries hard. It blusters, shatters, punches and stabs, but never wounds. Watchmen is safely caged inside its boxy frames, just out of reach. It’s ten times as violent as The Dark Knight, but ten times easier to watch.

It’s 1985 in New York, and a government-employed superhero called the Comedian (Edward Blake, played by Jeffrey Dean Morgan) is found dead on the street, thrown through the window of his high-rise apartment. The only other active member of the Watchmen, a particularly disturbed guy called Rorschach (Jackie Earle Haley), is convinced a “mask killer” is out to systematically destroy the band of former heroes. Rorschach has limited success convincing his old friend Dan Dreisberg (Nite Owl, played by Patrick Wilson) of his theory, and gets even less interest from Dr. Manhattan (Billy Crudup), a physicist who, during a terrible accident, morphed into a luminous radioactive giant with godlike power over mind and matter.

Dr. Manhattan is, it turns out, done with the whole business of being entangled in human affairs. Dumped by his girlfriend Laurie (Silk Spectre, played by Malin Ackerman) and weary of being the pillar of American national security, he teleports to his Martian den of zen, fully aware that his absence clears the way for  nuclear war between the U.S. and U.S.S.R. Rorschach, Nite Owl, and Silk Spectre, shaken by Dr. Manhattan’s sudden departure and the Comedian’s unexplainable murder, collect their masks and set about pursuing the predator they believe to be on their tracks.

Moore’s comic is wonderfully, deeply complex, fluidly following the past, present and futures of no less than five major characters and scores of their associates. Even beginning to sort the tangle would be a feat for a film director, and its careful arrangement and condensation are Snyder’s greatest—and only, I’m afraid—achievement. From the opening scene, where the murdered Comedian’s blood pools around his famous smiley face pin as the camera zooms up the side of his condominuim, the movie dutifully recreates panel after panel. Like all duties, it quickly becomes monotonous: conversations get cramped in unrelenting close-ups and actors stand around like subjects of a zoo exhibit. Once Watchmen slips into formula, punctuated awkwardly by Snyder’s trademark slow motion and by an incoherent, overbearing soundtrack, it never opens its eyes again.

The New York of Watchmen is far more menacing than Batman’s Gotham could ever imagine (even with Heath Ledger around), so why do we feel so safe on its streets? Even with a higher, more thoroughly mangled body count, Watchmen has none of what helped Christopher Nolan’s Batman movies overcome their jumbled storylines and plot holes: suffocating dramatic tension. The film doesn’t grasp the terror hanging over New York in its fictional 1985, when the city fully expected to be the first battlefield of World War III. Snyder’s street scenes ignore the frenzied, drive-by crazy—the constant babblings of a conspiracy-spotting newsstand clerk, a lesbian screaming “I want to be straight! I want to die!”—that make the comic so relentlessly, painfully nihilistic.

But the one-dimensional cast is worse. Despite being roundly unsympathetic, Moore’s conflicted heroes—their dysfunction, their frail, thwarted attempts at meaningful existence—made his story heartbreaking. They develop over panels of careful backstory, an onion-peeling effect lost in the film’s charitable but woefully condensed summary. Scenes like a climactic argument between Dr. Manhattan and Silk Spectre over the worth of human life—scenes that in the comic erupt after pages of escalation—feel wooden and overdramatic on screen. (It doesn’t help that Silk Spectre is “updated” with a choppy mod haircut, an Incredibles-style latex bodysuit, and penetrating lines like, “I can’t believe it happened!”) The heroes’ web of interpersonal entanglement gives the shouted conversations and vengeful killings meaning. Without the intimate details of those troubled histories, Watchmen’s argument in favor of a cruel, designer-less clockwork universe is more silly than crushing.

Snyder’s passion for the source material is perceptible in every frame, and he occasionally translates it into art (a couple on a couch reflected in a pair of spectacles, an execution intermittently observed through a swinging door). But Watchmen’s incredible detail doesn’t compensate for long, boring scenes full of pointlessly drawn-out fighting. Laid end-to-end, they add up to a long train of painless bloodletting.

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"Watchmen" opens nationwide on Friday. It is rated R for pervasive brutal violence, some grown-up words, and a few other grown-up things.