Maybe some of you weren’t paying attention when Jake Gyllenhaal was busy playing a seemingly mild-mannered crackpot who tracks his doppelganger in Enemy or a video-mad, dirty L.A. cop in End of Watch. But the guy who used to star in such movies as Prince of Persia and Love and Other Drugs has been doing his best screen work ever in indie-minded movies.

In Nightcrawler, he may have topped every one of those obsessive, deeply weird, dead eyed, highly mannered characterizations he’s tried-on so far. And, yeah, those guys he’s played in bigger movies like Zodiac and Prisoners, we’re looking at you. Gyllenhaal, alarmingly gaunt, bug-eyed and stringy-haired, goes pretty much full creepazoid in Nightcrawler. The movie marks a flashy, idiosyncratic directorial debut for its screenwriter, Dan Gilroy (The Bourne Legacy) and in it, Gyllenhaal plays Lou Bloom, a socially inept, sociopathic loner, thief, liar, and Google hound who grabs whatever he can while trying to survive on the fringes of Los Angeles. As shot in grimy, neon-lit splendor by Robert Elswit, Bloom’s capers include stealing and pawning construction equipment which, by sheer accident, leads him to penetrate the morally murky demi-world of “nightcrawlers,” bottom-feeding freelancers who’ll do anything to arrive first on the scene to film the bloodiest, most gruesome crime scenes, fires, and car crashes then sell the footage to local TV stations.

Bloom turns out to be a quick study, all eyes, ears and, so ambitious and totally lacking in scruples that he soon becomes a thorn in the side of a vet nightcrawler (Bill Paxton, who advises, “If it bleeds, it leads”) and a protégée of Nina (a very good Rene Russo), a ratings-hungry, aging local TV producer who practically salivates over Bloom’s in-your-face footage like when he shoves his camera in the face of an agonized woman yanked out of a burning car. Nina goads Leo to aspire to what, for her, is the right level of shock value for the footage for which she’s willing to write big checks: “A screaming woman running down the street with her throat slit.” A screaming white, suburban woman, that is.

Once the film’s amoral hero rises up the food chain and starts getting cocky, he awkwardly tries to seduce Russo over dinner (“I like older women,” he croons, chillingly unconvincingly) and, when that ploy gets shut down, he doubles down and brazenly shoots every bloody detail of a luxury neighborhood home invasion slaughter — even before the police arrive. What Gilroy and Gyllenhaal are up to here is a kind of amped-up Broadcast News meets Network meets Bringing Out the Dead for the TMZ and reality show era. The movie also plays like a jumped-up version of the 1950 noir flick Shakedown, in which Howard Duff plays a desperate photographer who’ll do anything and betray anyone to grab that great photo.

Look, watching Nightcrawler, the script’s illogic and inconsistencies could you pull you out of the action again and again. But damn if this thing doesn’t work on sheer nervous energy alone, thanks to its darkly funny tone, its director keeping things at thrill ride speed, its star working at fever pitch — equal parts Donnie Darko, Norman Bates and Rupert Pupkin — and terrific support from Russo and Riz Ahmed, the latter of whom plays the antihero’s battered employee. Creepy, nasty, often hilarious stuff, Nightcrawler shows Gyllenhaal exactly where he seems to want to be and having the time of his life while he’s at it. *** ½