If Rupert Pupkin and Travis Bickle, the demented characters essayed by Robert DeNiro in King of Comedy and Taxi Driver, raised a son, he might grow up to be something like Lou Bloom, the sociopath portrayed with a chilling zeal by Jake Gyllenhaal in Nightcrawler, the stunning directorial debut of screenwriter Dan Gilroy.

When we first meet Bloom, he's beating up the security guard who interrupts his theft of construction site materials, taking his victim's watch for good measure. It's quickly established that Bloom is a petty thief, not averse to using violence, but he's looking to move up in society, even offering his services for free to a site foreman who dismisses him with the cutting jibe "I'm not hiring a thief!" While driving through night time LA, Bloom stumbles across the scene of a roadside accident. A van pulls up and out jumps Joe Loder (Paxton), a freelance videographer who specialises in documenting crime and accident scenes, selling his footage on to the highest bidder among the city's various news networks. Inspired by Loder, Bloom acquires a police scanner and a second hand video camera, heading out into the LA night in search of ghoulish footage.

Thanks to his narcissistic personality and lack of ethics, Bloom quickly becomes the city's top footage finder, willing to cross both police lines and moral lines, not to mention breaking several laws along the way. Hiring a street kid (Ahmed) as his navigator, Bloom acquires a knack of arriving on the scene before the police, allowing him to rearrange the mise en scene for the benefit of his lens. He manipulates family photos on the fridge door of a homicide scene, and drags corpses under streetlamps to create a more dramatic shot.

Benefitting from Bloom's tactics is Nina (Russo), a previously struggling news showrunner whose career hits an all time high as viewers tune in en masse, thirsty for Bloom's latest blood-soaked segments. At first she encourages Bloom, egging him on by describing her news show as "a screaming naked girl, running down a street with her throat cut," (a juicy metaphor that Bloom takes all too literally) but she soon finds herself the victim of his ambition when he blackmails her into becoming his sexual partner, threatening to take his footage to a rival network should she spurn his advances.

Unless you're in charge of your own career, Gilroy seems to be suggesting, you're always going to have to prostitute yourself. As a journeyman screenwriter, I'm sure Gilroy has had to make a lot of compromises along the way before finally establishing enough clout to be awarded a stab at directing one of his own scripts. Freelancers from every trade will tell you the satisfaction of cashing a check earned for yourself rather than for an employer, and Gilroy sells the thrill of discovering you just might be able to strike out on your own, as Bloom builds up a collection of commissioned news segments, labelling the footage on his hard drive with lurid titles like 'Horror House'.

Gyllenhaal is one of America's most under-rated performers, and has generally chosen interesting roles, without falling into the Johnny Depp trap of essaying caricatures. Lou Bloom is the role of his career, and he has created a chilling portrait of a narcissist. The actor shed considerable weight for the role, and with his sunken eye-sockets and tightened flesh, takes on the appearance of a cyborg wearing a human skin mask stretched over its face. He plays Bloom as though he were an extra-terrestrial who learned of humanity through stumbling across self help videos. When Bloom smiles, it's never a natural muscle reaction; he's simply doing what he thinks a human should do at that moment. Watching his human interactions, particularly during a dinner "date" with a coerced Nina, is car crash black comedy at its best. Bloom's unbridled narcissism is uncomfortable to watch, but there's no way you're going to take your eyes off him. Not since Christian Bale's Patrick Bateman have we seen such a thoroughly engaging scuzzball.

It's never made explicit the era Gilroy has set his film in, and some of the technology seems contradictorily anachronistic (Paxton boasts about owning a 2.4 mega-pixel camera, yet Ahmed has a Sat Nav on his cellphone), but my best guess is the turn of the century, given the design of a search engine we catch frequent glimpses of. Despite the arbitrary setting, Nightcrawler feels very much like a product of the recession, with numerous references to the current culture of "internships", i.e "employees" working for free. With the current debate over how news outlets should handle the constant stream of gruesome videos filmed by ISIS, its examination of the bloodlust of modern media is now all too poignant.

As misanthropic as cinema gets, Nightcrawler will leave you craving a shower, but once you've dried off, you'll be drawn right back to it.