Thomasin McKenzie, left, and Anne Hathaway in “Eileen.” Jeong Park/Neon

Of Ottessa Moshfegh’s debut novel, “Eileen” – the 1964-set story of a mousy prison secretary outside Boston who discovers her darker self – reviewer Patrick Anderson wrote in The Washington Post that the 2015 book “may bore some readers and repulse others, but those with a yen for the perverse may well embrace its unsettling pleasures and exceptional writing.” Substitute “viewers” for “readers,” and “acting” for “writing,” and you’ll have a pretty accurate assessment of the new film adaptation, the sophomore feature from director William Oldroyd (“Lady Macbeth”), working from a script by Moshfegh and Luke Goebel.

In the title role, Thomasin McKenzie is never less than watchable. The 23-year-old New Zealand actress (who first made a splash, at 18, in “Leave No Trace” before moving on to such high-profile films as “Jojo Rabbit” and “Last Night in Soho”) still looks 13, but here she’s like the 13-year-old you want to keep an eye on when she’s behind your back. When we first meet the character, Eileen is sitting in a car surreptitiously watching a couple make out in a nearby vehicle. As Eileen gets worked up herself, she opens the door, scoops up a handful of snow and shoves it down the front of her conservatively tailored skirt. It’s an arresting if overheated metaphor for repressed desire, one that’s underscored when Eileen subsequently drives home in a car she must operate with the windows cracked – even in the dead of a New England winter – because otherwise the passenger compartment fills with smoke.

Back at the prison for teenage boys where Eileen works, she fantasizes about being ravished by a young guard (Owen Teague), appropriately named Randy. The way she looks at an inmate, Lee Polk (Sam Nivola), a boy who stabbed his father to death, is also more than slightly alarming. Eileen harbors her own thoughts of killing her father (Shea Whigham), a psychologically abusive, alcoholic former chief of police and widower, whose only engagement with Eileen – other than to berate her – is to ungraciously receive the fresh cigarettes and booze she picks up every day for him on the way home from work.

It’s a depressing routine. But it’s all about to change.

That change is precipitated by the arrival of a new prison psychologist: Anne Hathaway’s Dr. Miss Rebecca St. John, as the glamorous, Harvard-trained therapist is floridly introduced to the gobsmacked staff. Soon, Rebecca has befriended Eileen, who starts bathing more regularly and wearing lipstick. A relationship is about to bloom, in which Rebecca sees (and nurtures) something in Eileen that others do not. But what to call it? Friendship? Love? Obsession? Manipulation? All of the above? It’s the central dynamic of “Eileen,” and it will take the main character – and us – to startling places.

As with “Lady Macbeth,” Oldroyd displays an affinity for female characters who defy societal expectations. (That’s putting it mildly, in the 2016 film and in this one. Taboo and transgression abound.)

Advertisement

But the unorthodox, as pleasurable as it can be, is weak sauce. Despite “Eileen’s” bravura central performance – make that performances; Hathaway is great, too – the overstepping of boundaries feels slight.

At the center of it all, however, is McKenzie, embodying a weirdo in normie’s clothing (hand-me-downs from Eileen’s dead mother, which gradually go from drab to fab). One of the insults Eileen’s father casually deploys compares life to the movies – like this one, as it happens: In films, he tells her, there are the characters who make moves, the ones we can’t take our eyes off of. Then there are the characters, like Eileen, who just “fill in space.” At first glance, it seems like Rebecca is the one making the moves.

But Dad is dead wrong about his daughter, it turns out. And Rebecca is, early on, the only one who notices. “You really think you’re a normal person?” she asks her new protégée.

No, Eileen’s not normal. Not by a long shot. And McKenzie doesn’t just fill in space, she activates the whole darn movie, ultimately wrestling it away from Hathaway’s Rebecca, who enters the film like a whirlwind but is ultimately as surprised by Eileen’s depths – harboring deep reservoirs of resentment and long-stewing, suppressed fury – as we are. When Rebecca comments on the anger she senses after an interview with Lee’s mother (Marin Ireland, also good in a small but pivotal role), Eileen tells the shrink, with a shrug, “Everyone’s kind of angry here. It’s Massachusetts.”

It’s a funny line, in a film that is by turns darkly comic and disturbing, both sensations brought into vivid, caustic relief by the film’s mesmerizing star.