Jake Gyllenhaal plays a cameraman looking for trouble in a film by Dan Gilroy. Illustration by Boris Pelcer

The scariest thing about the new Jake Gyllenhaal film, “Nightcrawler,” is Jake Gyllenhaal. Or, to be precise, Jake Gyllenhaal’s eyes. They are sunk in their sockets. They have dispensed with blinking, and you can understand why; it would mean missing something important. They glare and they gleam, like the eyes of a man who is minutes away from death, furious with fever, and refusing to slip away in peace. Gyllenhaal’s character is named Lou Bloom, and the first time we meet him he’s on the prowl in Los Angeles—his cradle and his hunting ground. Darkness has fallen, and the leaves on the palm trees glitter. (Even the days in this movie feel like nights.) Lou’s skin is skull-pale, drawn as tight as a drum; starved of light, he sucks up every flicker of neon and moonshine, and his opening words are “I’m lost.” Does he think that he’s one of the damned already, or does the poor fellow simply need a map?

To begin with, I reckoned that he might be descended from Leopold Bloom, who roamed the Nighttown of “Ulysses.” Both Blooms wander and wonder, peering at their fellow-citizens. Somewhere along the way, though, the quizzical charity of Leopold has run dry, for Lou is an opportunist and a hermit: he lives alone, with no family ties, and no job. Nonetheless, he keeps busy. By night, he steals copper wire and sells it for scrap; he even steals manholes—a base-level crime, in every sense. One evening, stopping near an accident on the freeway, he finds not only cops but a film crew, catching the drama as it unrolls. A cameraman, Joe Loder (Bill Paxton), explains that he and his ilk tune in to police frequencies, and hurry to the scene. “If it bleeds, it leads,” Joe says, reciting an old mantra of his métier. Immediately, you can see what Lou is thinking: I could do that. “Thank you for taking the time to discuss what you do,” he replies, and you can see what Joe is thinking: This guy is nuts.

So Lou buys himself a cheap camcorder, plus a radio for listening in, and gets to work. The idea that such work is invasive, legally questionable, and morally foul never troubles him. In fact, it never occurs to him. Thus unfettered, he barges in where others fear to tread, and soon, armed with closeups of a carjacking victim expiring from a gunshot wound, he has his first scoop. It’s bought by Nina (Rene Russo), a producer at a local TV news station. “The quality’s for shit,” she says, but she warms to Lou, and schools him in the trade. Specifically, she designates the best kind of victim to film (white, well off, from a pleasant neighborhood), and the ideal image toward which her profession strives: “A screaming woman, running down the street, with her throat cut.”

“Nightcrawler,” which was written and directed by Dan Gilroy, provides ample cause for alarm. Viewers who recently booked a vacation in L.A. will come out of the movie and cancel their reservation. Yet there is so much else going on here, primed to grip and entrap. For a start, the whole thing is dangerously beautiful. It was shot both digitally and on film, as was Michael Mann’s “Collateral,” another nervous nocturnal thriller, set in the same city. That film throbbed like a headache, whereas “Nightcrawler,” thanks to its director of photography, Robert Elswit, whose previous credits include “There Will Be Blood” and “Good Night, and Good Luck,” has more of a racing pulse. The momentum and clarity leave us with a sense that we have seen something being reported, not dreamed up—a vital advantage, in a story about the ravening quest for news. There are moments, as Lou homes in on yet another ghastly incident, like a fly approaching a plate of meat, when I could swear that I smelled the night air.

“Nightcrawler” marks Gilroy’s début as a director. He wrote the screenplay for “The Bourne Legacy” with his brother Tony, and although “Nightcrawler” is much less of an action movie, the pacing of the plot is remarkably adept, and we never have long to wait before the next bend in the road. More often than not, this being Los Angeles, that means a real bend. Lucky Lou reaches a smashed-up vehicle before anyone else, and, having taken a minute to weigh his options, drags the unconscious body of the victim into the pool of the headlights, the better to frame the disaster in style and give viewers a clearer look. He is like a Billy Wilder hero (Kirk Douglas’s unscrupulous reporter, say, from “Ace in the Hole”), transplanted to the land of David Lynch. The difference is that, where Lynch, in “Wild at Heart” and “Mulholland Drive,” follows those who stagger away from car wrecks, hurt and haunted, Gilroy remains with the haunter, who only stands and stares.

The crux of the movie comes from a single question. “You’re going to show this?” Nina’s colleague asks, when he watches what Lou has to offer. Needless to say, the station goes ahead and airs it, adding a tagline—“Viewer discretion is advised”—that works as both caution and catnip. Later, when Lou misses a story, and tries to compensate with a feeble shocker from the second tier (“I have the stabbing in Corona”), Nina explains, in her steeliest tones, what is required: “I want something people can’t turn away from.” Gilroy may be overstating his case here, but such heated excess allows him to join a debate that was set in motion two and a half thousand years ago. To the Greek mind, the purgative effect of horrific events was deepened, not curbed, when they occurred offstage; even now, a production of “Medea” that showed her slaughtering her children, rather than running in red-handed once the deed was done, would be disrespectful to Euripides, and to the dead. In the world according to “Nightcrawler,” though, where network news is a serial offender against taste, the idea of respect is about as relevant as a sword fight, and there is no such place as offstage. There is only appetite, and the ratings spike to be had from sating it. Viewer discretion is a joke. Nina, who would have fired Medea for being a soft touch, has a point: if you let people’s attention drift, or block their view, or refuse to show the worst and then claim to be operating in their best interests, they will turn away, or switch off. Hence Nina’s shiver of expectation, one evening, when Lou arrives at her office, and declares, “I have something.”

The something turns out to be a multiple murder, in the Valley. Again, Lou is the first responder, and, in addition to filming the bloodbath from TV-friendly angles, he has the wit to engineer a second act. Having glimpsed the perpetrators’ license plate, he tracks them down, alerts the authorities, and settles back, camera at the ready, to capture the showdown. In short, he is all but directing his own movie, and he brings the footage to Nina in person, “to improve my bargaining position.” This is what I liked most about “Nightcrawler”—what lends it a cultural charge that was missing from a film like “Gone Girl,” and what makes Lou’s story so much more than a parable of prurience. The film has the dirty rustle of money. In his own mind, Lou is an entrepreneur, in a fine, self-improving American tradition. “I work for myself,” he says to Nina, at their first meeting. “I run a successful TV news business,” he says to Rick (Riz Ahmed), a quaking soul whom he hires as an assistant (“It’s an internship”), and later anoints as executive vice-president, amid plans to “expand to the next level.” Gyllenhaal wipes every fleck of irony from his voice as he makes these announcements, and you can see why. To him, feeding on carrion is not a sickness, or an outrage; it’s just corporate practice.