A Cure for Wellness opens with a foreboding shot of a nightmarish edifice looming over the viewer at a canted angle. It’s not the creepy Swiss sanatorium where most of Gore Verbinski’s demented new film is set. No, it’s a Manhattan skyscraper, where a stressed-out office worker (Craig Wroe) takes a drink from the water cooler, then violently keels over and dies from a heart attack as the score thuds and groans furiously. Verbinski (Pirates of the Caribbean, The Ring) has never been a subtle filmmaker, but even by his standards A Cure for Wellness is bold—an epically long, giddily violent piece of Gothic storytelling, crammed to the gills with beautiful camerawork, obvious symbolism, and lots and lots of eels.

That Manhattan office is also the workplace of Lockhart (Dane DeHaan), a young executive who seems well on his way toward collapsing at his desk. The pale, drawn employee constantly chewing on nicotine gum is a role suited to the twitchy DeHaan, who has the look of someone in need of a serious spa day. With his co-worker dead, Lockhart is tapped to travel to Switzerland and retrieve the company’s CEO, who has retreated to a mysterious sanatorium and promised never to return to the empty life of big-city business.

Who can blame him? Verbinski shoots New York as a bleak, drab underworld. The “wellness spa” that Lockhart travels to—nestled in the Swiss Alps, conveniently located miles from any proper civilization (or cellphone signal)—is a comparative paradise. But, of course, all is not well atop the mountain, despite the stunning vistas. Like everyone else there, Lockhart is a person of means, summoned by some unspeakable force, to be “cured” of his modern woes. Though Verbinski and his co-writer Justin Haythe take plenty of time to unravel the dark secrets of the spa, they are not coy about its overall malevolence. From the second he walks in, the trap is sprung.

But it’s hard not to root for his comeuppance. It’s why Verbinski begins with the big scary city, and it’s why he’s decided to make a film in which the protagonist is an irritable jerk, barking at orderlies and demanding that his boss be produced at once, so that he can be dragged by his ear back to New York. Lockhart only half-listens as his driver tells him the history of the spa, built on the site of a castle that was destroyed by angry villagers when its lord was caught kidnapping people for nefarious purposes. Lockhart absentmindedly signs any form that’s put in front of him, and when offered a tall glass of the spa’s famed water by the ominous Dr. Heinreich Volmer (Jason Isaacs), he happily sucks it down.

Lockhart is like a wayward teen wandering into an abandoned house at the start of a slasher film, then inexplicably deciding to walk upstairs when he hears a creepy noise. You want to scream “don’t sign any paperwork!” at the screen, but you’re also rooting for his just deserts all the same. Soon enough, Lockhart finds himself trapped at the spa, after getting in a car accident when he tries to leave. He begins to delve into the institution’s deeper mysteries—where his boss is, what’s so special about the water everyone’s drinking, the origins of the “illness” he and every other patient have been diagnosed with, who the odd girl (Mia Goth) moping around the grounds is, and whether all those eels he keeps seeing are real or imaginary.

In case you haven’t seen any of the promotional materials for A Cure for Wellness, eels play a major part in the film. The slithery creatures are in the sensory-deprivation tanks the patients chill out in, they’re in the strange visions Lockhart keeps having at night, and, yes, they’re rustling around in his toilet tank (quite a lot of them, in fact). There are plenty of other mysteries, most of them obvious, but Verbinski is having more fun with the dizzying imagery than with the unfolding plot. Lockhart’s investigations are just a series of unsettling set pieces, almost all of which end with doctors and nurses, dressed in white, escorting him back to his room or strapping him down for some new, terrifying form of treatment.

A Cure for Wellness is unbelievably expensive-looking considering how violent and intense it is—there’s one scene of impromptu dental work that genuinely shocked me by not cutting away at its most horrifying moment. It’s also, thematically, a truly dark and depressed work. The film seems to argue that the only real fix for our capital-obsessed society is genuine madness and that dull depression can be transformed through brutal torment. Not all of it makes sense, but as Hollywood grows more homogenous and risk-averse, it’s a delight to see Verbinski scare up a giant budget for his grandly realized Lovecraftian visions.

The film’s climax doesn’t quite do enough to justify the 145-minute running time; in some ways, it’s annoyingly pedestrian, with Verbinski abandoning his most surreal visuals to conclude on a note that feels pat. But A Cure for Wellness isn’t arresting because of its story—it’s a simple haunted-house tale, just realized on a larger scale, crammed with attention to detail and charged with a jolting, unnerving atmosphere. This is a movie where a drink of water feels sinister, where a walk through the sauna becomes a descent into hell. And don’t forget the eels.