The axiom animating television news — "If it bleeds, it leads" — often leaves you wondering just who gets stained in the process.

Particularly in the wake of frenzied, exhaustive coverage of Ebola, school shootings and spasms of small-town violence, are viewers implicit in the thirst for ever gorier news stories, or should those providing the information exhibit restraint, rather than a hunger for ratings?

With his timely new film "Nightcrawler," writer-director Dan Gilroy ("The Bourne Legacy," "Real Steel") entertains such queries, following Louis Bloom into the darkest shadows of nocturnal Los Angeles, while balancing satire and grim horror in regards to the dirty business of creating must-see TV.

Bloom, as played by Jake Gyllenhaal, seems a high-functioning sociopath as the film begins, struggling to find a job into which he can pour his overwhelming focus and determination.

After happening upon a dramatic, fiery car accident on the highway, and crossing paths with run-and-gun videographer Joe Loder (Bill Paxton), Bloom becomes fixated on documenting the mayhem unfolding every night across Los Angeles.

His early attempts at capturing fires, car crashes and shootings are played for laughs, but it’s not long before the chuckles begin to stick in the throat.

Bloom, working alongside hesitant collaborator Rick (a terrific Riz Ahmed), plunges deeper into the world of freelance crime journalism and begins to play fast and loose with the law.

Bloom is egged on by KWLA news director Nina Romina (Rene Russo in a superb turn), a ruthless, ratings-driven veteran eager for all the gruesome footage Bloom can bring her.

‘NIGHTCRAWLER’ Rated: R Opens Friday

Their increasingly complicated relationship becomes a gripping secondary story to Bloom’s own long journey into night, as savvy about newsroom dynamics as it is leveraging sex for power.

For all its biting commentary about the high cost of sensationalizing the news, "Nightcrawler" serves a phenomenal showcase for Gyllenhaal, who is never less than riveting as Bloom. A full package of tics, tightly coiled tension and breathless patter, this self-taught entrepreneur stops at nothing, evoking a Travis Bickle for the TMZ age. ("Maybe it’s not that I don’t understand people, but that I don’t like them," Bloom observes at one point.)

Gyllenhaal gives Bloom a manic gleam, making it easy to see why, although he may unsettle those he encounters, he also proves irresistible. The actor is complemented by his castmates: Russo excels as the seen-it-all news director, uninterested in anything other than dominating the ratings and holding onto her job, while Ahmed is heartbreaking as Bloom’s tentative collaborator, forever unsure of where he’s being led.

Shooting on location across Los Angeles, director of photography Robert Elswit brings a queasy slickness to the screen, not shying away from some of the city’s rougher edges, but instead making viewers feel as though they’re racing down the same mean streets as the characters.

Gilroy, directing from his own screenplay, manages to maintain a tricky balance between comedy, drama and horror. "Nightcrawler" considers the absurdity of it all, even as it rages against those who perpetuate such crassness.

The film’s thesis is delivered by Russo, who describes the TV station’s product to Bloom: "The news is like a screaming woman, running down the street with her throat cut."

An ugly image, and one the riveting "Nightcrawler" spends its entire running time questioning.