Anne Hathaway, left, and Thomasin McKenzie in Eileen (Sundance Institute)

Movies and TV these days abound with trendy, edgy-adjacent, but ultimately shallow psychological thrillers. So you could get a pass for thinking that William Oldroyd’s Eileen is going to be another faux-shocking exercise with lots of tease and not much impact: Carol Lite, or The Whale in a size 4 dress. Wrong. Oldroyd directed 2016’s chilling Lady Macbeth, and he brings a touch of that film’s beady-eyed harshness to a wild ride through some deep-black mental spaces. Self-hate, self-harm, and a sicko plot twist are Eileen’s way stations, along with a few tantalizing glimpses of the redemptive power of love.

For a log line, try “Introvert is swept off her feet by sexy woman doctor she meets at men’s madhouse.” It’s a brutal winter in mid-1960s Massachusetts, where flinty-faced young Eileen (Thomasin McKenzie) is an aide at a miserable institution for those once known as the criminally insane. As dowdy as only a born New Englander can be, Eileen gets nothing but scorn from co-workers and puts up with horrific abuse from her father, a volatile, snarling ex-cop (Shea Whigham). But there’s a defiance under Eileen’s buttoned lip—sexual and violent fantasies writhe beneath her harassed exterior. When a gorgeous blond woman psychiatrist (Anne Hathaway) arrives at the hospital, the good doctor immediately spots the darkness within Eileen. Soon there’s a spark at the asylum. An extended hot flirtation in a bar. And then a turning point where the two conspire to carry out something eviler than either can grasp.

Eileen doles out darkness in medicinal spoonfuls with scenes of realistic-looking vomiting, domestic misery, and a few spitefully comic fake-outs (until one turns out to be terrifyingly not fake). Then the film throws the viewer off balance by tossing in seductive woo as the two women circle each other as well as moments of infatuation that can make even the nastiest life feel sunnier and more promising—blonde, beguiling Hathaway has never been hotter or delivered a headier performance. The music punches up the contrast with a smart, moody jazz soundtrack interspersed with dreamy, mercifully lesser-known ’60s pop hits. The cinematography is grainy and gray, so when a platinum hairdo or ray of light pierces through the murk, it feels like a beam from heaven.

When the film’s balancing act shifts back to darkness, it happens at first with a few disturbing hints and then inescapably, like a solar eclipse. Some viewers may feel buffeted to and fro by the prevailing mood swings, or even dragged to hell. Eileen packs a punch. It’s a backhanded female revenge fantasy and a folie à deux.

Oldroyd’s film may not always ring strictly believable. Its ending could be seen as a bit of a cop-out. It toys with humor that is very funny when it hits, but seems pandering when it doesn’t. Still, there are moments when Eileen has the power to plunge us into extreme and enveloping emotional states—and unlike a lot of movies with similar aims, uses it.