In the novel In Secret is based on, the central character, Thérèse Raquin, lives with her strict aunt and sickly cousin in rural 19th century France and is eager to get some action. So first-time director Charlie Stratton demonstrates this by having Thérèse (Elizabeth Olsen) all but hump the ground as she spies on the shirtless gardener. Her aunt (Jessica Lange), meanwhile, is all about children of any age being seen and not heard—and then there’s that title—thus she’s seen embroidering a cloth with the phrase “Don’t make a sound, keep quiet.”

So Stratton isn’t exactly subtle in his directorial debut, whose script he wrote. (His only previous screenwriting credit is contributing to 2009’s awful Formosa Betrayed.) But considering he’s a rookie, the rest of the film is promising. Of course, he lucked out with an of-the-moment cast: Olsen’s an indie It Girl, Lange’s been scaring the fuck out of American Horror Story viewers for three seasons, and then there’s dreamy Oscar Isaac, fresh from his breakout role in the Coen Brothers’ Inside Llewyn Davis, playing Thérèse’s secret, Laurent. Oh yeah, and Thérèse is married to her consumptive cousin, Camille, played by Tom Felton. But anyone who swoons over the Harry Potter franchise’s Draco Malfoy is either too young for In Secret or, well, has issues.

That Thérèse and family friend Laurent become lovers after the trio move to a dreary, Diagon Alley–like part of Paris is the film’s first secret. And if you’ve seen the trailer (or, naturally, are familiar with either the book or the play adapted from it), you know there’s another—one that’s darker, more chilling, and proves that Thérèse and Laurent’s star-crossed, endless passion can indeed come to an end, ironically when they get what they want.

In Secret, then, is more thriller than period-piece romance. (Had to be a reason Keira Knightley wasn’t cast.) Even though the story takes place in France, the actors maintain light English accents that are serviceable if you don’t concern yourself with why they’re not French. The second half of the film sometimes becomes a guessing game of who’s-pissed-at-whom-and-why. (Don’t Thérèse and Laurent love each other? WTH?) But it also turns into a tension-filled creepshow, one that Lange was well-prepared to dominate. And she does—especially after her character has a stroke that renders her mute. Between the scattered cheap jumps and Lange’s disturbing portrayal of an elder whose body is crooked and seemingly catatonic—yet who’s bursting to shout out what the couple doesn’t think she knows—In Secret is enough to give you the vapors.