Mary Bronstein returns to the big screen 17 years after her debut feature, Yeast (2008), which is among the essential films of the mumblecore subgenre. This time she shifts to a much more anxiety-inducing, dark horror/comedy. The writer/director calls her movie not autobiographical, but “emotionally true” to her personal experiences. Her deeply subjective film plunges us into a mother’s feelings of suffocation, dread, guilt, helplessness, loneliness, and, at the same time, her will to hold everything together.

Despite working as a therapist, Linda (Rose Byrne) lacks a support system, such as friends or family. Her husband (Christian Slater) is available only through phone calls while he is away for work. Her own therapist (a strong dramatic debut performance by comedian Conan O’Brien) is the only person she turns to. In between sessions with her patients, she constantly runs down the hall, begging him to provide answers to her problems; he prefers to keep his distance and remains silent regarding her expectations of him.

Linda’s struggles stem from her underweight daughter’s chronic illness, which is never specified. The girl has to be intubated until she reaches her weight goal. When the doctor (played by Mary Bronstein) says coldly, “We have to reassess the levels of care,” Linda takes it personally and internalizes the words as an indication that she’s a failing mother. Her problems increase with the collapse of her bedroom ceiling, causing her and her daughter to move to a no-frills motel. Linda’s deep-seated belief in her inadequacy becomes a cycle of self-sabotage—getting drunk on wine in the motel’s parking lot or locking herself out of the motel room.

The introduction of Linda’s patient, Caroline (Danielle Macdonald), throws the introspective protagonist into an ethical conundrum. Caroline, a new mother, likely suffers from postpartum depression and is extremely anxious about the well-being of her newborn baby. Her worries vary from not being a good enough mother to the possibility of her baby being murdered by a psychotic nanny. Caroline’s experiences with motherhood draw distant yet relatable parallels with Linda’s, including an indifferent husband who frowns upon her caregiving abilities. (There are also references to Andrea Yates, who drowned five of her children, and Mommie Dearest throughout). Bronstein constructs a Russian nesting doll of a tenuous (and failing) support system, in which Caroline relies on Linda while Linda relies on her therapist to deal with Caroline’s issues for which she doesn’t have a therapeutic solution.

Byrne has been given the opportunity here to subtly portray someone who’s not easy to understand or root for. The rapport with motel worker James (A$AP Rocky) brings out a completely different side of Linda. He offers care that is laid-back and unexpected, which throws her off and intrigues her in equal parts. Bronstein leaves Byrne room to breathe and develop a sophisticated character, who is perpetually on the edge of a breakdown.

Light and the sea are often used as visual metaphors, connecting Linda spiritually with her memories of motherhood and her escape from it. Dust particles in streams of light coming from her collapsed roof are only visible to her, as are open portals into the dark, whereas the sea offers a refuge from all the noise around her. The sound design reinforces and heightens Linda’s apprehension. Her daughter is largely heard only as a needy, talkative, and fearful child, heightening Linda’s anxiety. Other characters are often filmed in tight close-ups, enhancing the claustrophobic atmosphere we feel alongside Linda. We also feel her anxiety at a steady and unrelenting rate, which, thanks to the excellent editing, produces a fast-paced and thoroughly tense movie.

Blending personal emotion with an impressive visual language, Bronstein creates a vivid and horrifying journey. Linda is a character of rare complexity and moral ambiguity who honestly comes to life through Byrne’s compelling performance. Bronstein bravely and imaginatively confronts head-on issues that many films would shy away from. In doing so, she offers a perspective that is genuine and empathetic.