It’s been 17 years since viewers were shocked to see Woody Harrelson as a full-blooded monster (thank you, Oliver Stone). But it’s still hard to picture him as a straight-up bad guy. Most of the villains he plays are amoral opportunists who don’t quite deserve the appellation “evil,” like the bounty hunter in No Country for Old Men. Even when playing the cynical burial unit captain in The Messenger, some of his darkest work, Harrelson twigged to the character’s vulnerability. There’s something different at play in Rampart, which is not just the great starring role he’s deserved for a long time, but also an opportunity for him to explore depravity in a way he hasn’t outside of Natural Born Killers.

The new film by the curiously talented Oren Moverman (who wrote and directed The Messenger) is Harrelson’s show from the start. The story is built around the rapidly disintegrating life of his Dave Brown, an LAPD officer who runs afoul of the brass after being videotaped while he nearly clubs a man to death on a city street. The circling net of investigation into Brown’s cesspool past is set against the backdrop of the Rampart Division corruption scandal of the late 1990s. Cowriter James Ellroy used the same era for another corrupt cops story, Dark Blue, which unspooled amid the gathering storm of the Rodney King riots. Here, however, the history is backdrop and the focus is on Brown and the people, mostly women, who are drawn into his orbit and end up paying for that proximity.

Like most protagonists in Ellroy’s fiction, Brown is an angry coil of temper that gets unleashed on whatever minor criminal (or ordinary civilian) who happens to get in his way. Also like many of Ellroy’s men, particularly from the L.A. Quartet novels, Brown is an inveterate racist, compulsive womanizer, and not above hiring his gun out for dirty cash on the side. The film also shows how he’s rewarded for his brutality: when Brown walks through the precinct on his way to an official dressing down for the beating, he’s given an ovation by his fellow officers. After being harangued by a superior (Sigourney Weaver), he makes it clear that if pressed, he’ll go to court and show off his legal degree and Vietnam veteran status and also bring the department down with him. “I’ll have a show on Fox News in a week,” he concludes with a rapacious grin. Too smart for the job he has but too self-destructive to get out of it, Brown only uses this threat to get what he wants. Really, he can’t imagine life outside the LAPD.

He loves what he does, and that sets him apart from Ellroy’s usual doomed bulls. Brown prowls the city streets like some disgruntled hitman, head shaved clean as a bullet and eyes hidden behind sunglasses. But he’s not only a macho cop stereotype: while Brown lives in the expected grungy, barely decorated single man’s room, it’s located next door to a bucolic stucco house where both of his ex-wives (Anne Heche and Cynthia Nixon) live with their daughters. Brown floats in and out of this domestic life in a restive manner, not quite able to deal with his lack of control over the women’s lives, but unwilling to abandon the home’s warmth and curious predictability. In these scenes, Moverman’s camera hovers on the edges of interactions, as dialogue overlaps in a loose, Altmanesque muddle, an indication of Brown’s own lack of focus.

Again and again, Brown’s malevolence is revealed indirectly. We learn little about his past, save what he lets out as occasional conversation. (He regularly trots out one tidbit, about an accused serial rapist whom Brown supposedly murdered years before, as a pickup line.) For a time, Brown seems happiest in those moments when nothing’s happening, whether he’s hanging out with his daughters or lurking at the bar. We might imagine, briefly, that he’s just the cop of legend who goes too far with the criminals, but only because he cares too much.

But Rampart never lets us forget that Brown’s past—no matter how obliquely rendered—isn’t ever past. His hungers, for cash or drink or carnal nights, will ultimately swallow him whole. His one-night stands with a self-hating defense attorney (Robin Wright) are doomed, his friendly chats with a handicapped beggar (Ben Foster) likely to end in bloodshed.

If they’re not spelled out, these dangers create a kind of deep background, emerging from Moverman’s feel for the literary. The dialogue sounds rich and tempered, capturing some of the harsh snap of Ellroy’s prose (and reminding us of Moverman’s script for the great and under-seen Jesus’ Son, which made frightening music out of Denis Johnson’s novel in much the same way). His directing adds to this texture, emphasizing the tangled lines of dialogue with layered, slightly surreal cinematography, to give a dreamlike gloss to Brown’s downward spiral.

For all these strengths, Rampart is destined to come and go without leaving much of a trace. That’s not because of its occasional defects—like some sketchy plotting or a poorly handled club scene that might have been lifted from any number of other, less intelligent films—but because of the things it does right. It’s an impressionistic character study dressed up like a cop film, and viewers looking for one or the other only will come away disappointed.