Emotional abuse rarely gets the subtle, sensitive treatment on screen as it does in Mary Nighy’s thoughtful if uneven drama “Alice, Darling,” starring Anna Kendrick.

At first, we don’t know the source of unease that grips Alice (Kendrick), a young professional living in an unnamed city. When she meets her longtime friends Sophia (Wunmi Mosaku) and Tess (Kaniehtiio Horn), she arrives burdened by preoccupation. In the bathroom, she anxiously twirls her hair, pulling tufts out. Later, meeting her artist boyfriend Simon (Charlie Carrick), she nervously mouths words to herself as practice before saying them aloud to him.

What we begin to grasp is that Alice’s mind is occupied, unsettlingly, by Simon, whether she’s with him or not. “Alice, Darling,” which opens in theaters Friday, is a kind of psychological home invasion film, movingly played with twitchy nerves from head to toe by Kendrick in a performance starkly more dramatically intense than her usually more comic screen roles.

Movies about romance-turned-nightmare often slide closer to slasher territory — and the heavy-handed score by Owen Pallett seems to think “Alice, Darling” is one of those, too. But the movie, penned by Alanna Francis, isn’t built around an increasingly disturbing series of encounters. Although it has the shape of a thriller, it isn’t really one. Outside of a few flashbacks, Simon is hardly in the movie, at all.

Instead, Nighy’s film is grounded in the psychology of Alice and the support she gleans from her friends. “Alice, Darling” unravels during the trio’s weeklong getaway to a lakeside cottage, a vacation that Alice — sensing her boyfriend’s likely disapproval — has told him is a business trip.

Their interactions are prickly at first, at least between Alice and Tess (Horn). In her feature debut, Nighy (daughter of Bill Nighy) succeeds most in capturing these complicated relationships. The three women have known each other so long that their interactions are filled with sisterly tension. But it’s Tess and Sophie (a very good Mosaku) who recognize the pain Alice is hiding even from herself. Simon isn’t a horror film monster, it turns out — but he is a cruel, controlling jerk whose manipulation of Alice has shaken and confused her.

“Alice, Darling” is a little thinly sketched and lacks a strong sense of directorial perspective. But, in shirking genre contrivance, Nighy gets the most essential thing right, authentically capturing a not-uncommon real-life experience with rare nuance. Kendrick gives one of her best and most wrenching performances as a woman riddled with self-doubt clawing her way out of a destructive codependency. That it comes from an actor of such witty confidence makes Kendrick’s performance only more affecting.

“Alice, Darling,” a Lionsgate release, is rated R by the Motion Picture Association for language and some sexual content. Running time: 90 minutes. Two and a half stars out of four.