Haley Bennett lays it all out there in “Swallow,” a quietly disturbing, hard-to-watch psychological drama about an unhappy woman in a controlling marriage whose unhappiness manifests itself in the compulsive disorder, pica.

And even if this dark film hunts for what seem to be simplistic cause-and-effect solutions to its heroine’s plight, it still makes for a tense and intimate thriller. Because pica, as our heroine Hunter demonstrates, is a harrowing form of self-harm.

Meek, mousey housewife Hunter is treated with little respect or deference by her rich husband Richie (Austin Stowell of “Fantasy Island”) and his richer, condescending parents (Elizabeth Marvel, David Rasche).

Bennett, of “The Red Sea Diving Resort” and “The Girl on the Train,” shows us a world of hurt in her eyes. Hunter speaks quietly, makes sure she is beautifully turned-out at all times, prepares gourmet meals for her star-in-daddy’s-business husband and hides whatever emptiness or pain she’s carrying around.

Her mother-in-law is Mrs. “You would look so pretty with long hair. You should grow it out. Richie likes his girls with long beautiful hair.”

She’s of the opinion that Hunter had little going on in her life, so “Lucky break, you meeting my son.”

Her father-in-law doesn’t even bother to insult her.

So Hunter starts eating things she shouldn’t — a little dirt here, a lot there, testing the idea of swallowing a marble, a thumbtack and worse.

She fastidiously (and grossly) “collects” the items after they’ve passed through her system successfully. Yes, it is painful.

But as she’s pregnant, sooner or later a doctor is going to figure out what she’s doing. A shrink is consulted. And still she cannot stop. With every fresh exercise of control, every perceived betrayal, Hunter seems more desperate and lost.

Writer-director Carlo Mirabella-Davis, who directed by “Once” sequel “The Swell Season,” keeps the focus on Hunter and the camera tight as she ponders this lock, that battery, “the textures” of things she puts in her mouth.

Yes, it is squirm-inducing.

Bennett, who produced “Swallow,” keeps her character’s suffering and emotions submerged, but close to the surface. And every now and then there’s an explosion.

There’s a touch of “The Invisible Man” to this unsettling story of the misery of being married to a cruel control freak.

But “Swallow,” for all its People Magazine psychoanalysis, is harrowing in different ways and gripping in its myopia. All Hunter has is this mania for “control” of one thing in her life — what she puts in her mouth. All we have is worry over her mental health, and discomfort in confronting it.

MPAA Rating: R for language, some sexuality and disturbing behavior.

Cast: Haley Bennett, Austin Stowell, Denis O’Hare, David Rasche, Elizabeth Marvel and Zabryna Guevara

Credits: Written and directed by Carlo Mirabella-Davis. An IFC release.

Running time: 1:35