Two teen girls forge a dark friendship in the tense, blackly comic Thoroughbreds

Given that it begins, essentially, with two teenage girls studying vocabulary in preparation for the SATs, maybe it’s not such an unfair nitpick to complain that Thoroughbreds should have stuck with its original title. When the film premiered at Sundance some 14 months ago, it went by just Thoroughbred, singular—an adjective, a noun, and a moniker of multiple meanings, referring not just to the poor, dead horse around which its backstory unnervingly coils, but also to the aforementioned teens, “very educated and skilled” by dictionary definition, as bred for success in suburban, upper-crust Connecticut as the prized beasts they stable. It’s a small change, that pesky, pluralizing “s” affixed to the end of the title. To harp on it is to acknowledge how carefully Cory Finley’s fiendishly clever, savagely funny directorial debut otherwise chooses its words, along with its shots, its cuts, and every twist of its proverbial knife.

In all fairness, there are two of them: a pair of estranged childhood companions whose friendship is uncomfortably rekindled on the cusp of adulthood. Lily, a chipper prep-school overachiever played by The Witch and Split star Anya Taylor-Joy, has agreed to tutor Amanda (Olivia Cooke, the dying girl of Me And Earl And The Dying Girl), mostly because the latter’s mother has paid her handsomely to do so. Amanda is a social pariah, and not for nothing; like the disturbed hero of Equus, she’s done a ghastly thing to a horse—an incident the other kids gossip about relentlessly. During the girls’ obligatory reunion, Amanda makes a casual confession: She feels nothing about anything, and never really has—no anger, no sadness, no joy, certainly nothing like remorse over that nasty business with the family steed. She’s a fascinating character: a spookily self-aware sociopath who’s transformed her “condition” into a kind of infallible bullshit detector. Bored of faking niceties and the feelings she doesn’t possess, she cuts through her old friend’s pretenses with dry nonchalance, whacking away Lily’s white lies, her feigned good manners and polite-society politeness.

For a while, we could be watching a twisted mismatched-buddy comedy, one about an uptight do-gooder under both social and financial obligation to tolerate the off-putting tactlessness of this strange girl from her past. But Thoroughbreds isn’t so easily pegged. It sees, as Lily eventually does, an upside to a friend who can’t be hurt or offended, a friend for whom total honesty is possible. Plus, maybe Lily isn’t the model student and well-adjusted choir girl she appears to be. Reworking his own un-produced stage play, Finley moves fluidly into thriller territory, as the girls’ relationship skips straight from strained friendship to something darker. The high school Hitchcock plot, distantly blood-related to the adolescent noir of Brick, involves Lily’s stepfather (Paul Sparks), an icy fitness freak no less banally loathsome for how essentially right he is about his stepdaughter’s selfishness. (“Empathy isn’t your strong suit,” Amanda concurs.) The conspiracy that emerges also entangles a local dirtbag drug-dealer played by, in what now stands as his final screen appearance, the late Anton Yelchin. It’s a fine swan song: All idiotic overconfidence and frazzled fall-guy desperation, his Tim is a memorable loser.

In the pop of its conversation and the slimness of its cast (the film often plays like a two-hander), Thoroughbreds doesn’t disguise its theatrical origins. But there’s nothing stagy about the staging. Finley’s direction is as confident and razor-sharp as his dialogue, his camera gliding with predatory precision around every corner of Lily’s spacious suburban castle, locking on pertinent details like a hawk spotting a kill, and setting up little miniature triumphs of execution, including a set piece involving the triggering of automatic floodlights. It’s rare, furthermore, to encounter any film, let alone an economically mounted first feature, so attuned to the suggestive power of sound design. Finley does wonders with offscreen noise, building suspense sequences around the muffled whirr of an exercise machine and the delayed chirp of an instant message. At times, the sonic elements—the incessant tap of a finger, the rhythmic drip of a faucet—bleed into Erik Friedlander’s anxiously atonal score, a Jonny Greenwood-esque symphony of clicks, skitters, and booms.

Thoroughbreds, in other words, has been made with diabolical craft and intelligence, the kind that marks Finley as a major new American talent. But it’s no empty exercise, no mere calling card. The style all comes in service of the central relationship and the superb performances that bring it to bewitching life. Proving that the bubbling cauldron of intensity she stirred in The Witch was no fluke, Taylor-Joy peels back Lily’s layers of well-honed artifice over four plot-pivoting chapters. Cooke, meanwhile, plays Amanda’s emotional blankness to a deadpan hilt, while still managing to make her oddly likable, ultimately even sympathetic—she’s a human android trying to sort out her place in a world she sees with a mercenary clarity. Swirling at the film’s center, like blood circling a drain, is a provocative suggestion: We’re all doing an imitation of “normal,” but only some of us know it and only some of us are passing. Maybe the plurality of the new title is fitting after all.