The film opens with a short series of images of hospitals, dead bodies, landscapes, a hand impaled by a nail, and a bespectacled young boy lying uncomfortably under a thin sheet. (The shot of an erect penis was removed for distribution outside Scandinavia.) A young nurse (Bibi Andersson) is assigned to look after a great actress, Elizabeth (Liv Ullman), who had been playing Electra to critical success. Elizabeth is completely mute, but the psychiatrists cannot detect any discrete pathology and have no diagnosis.

At first the nurse worries that the case may be too complicated for her, because of the difference in age and experience. The pair are sent to the doctor's summer cottage by the sea. The actress remains silent, but her nurse chatters endlessly, trying to draw out the patient. Eventually, in a complete reversal of psychotherapeutic roles, she is compulsively confiding her fears and intimate secrets of sexual adventures.

To her horror, she reads a letter written by Elizabeth to the psychiatrist that describes the confessions as nothing more than amusing diversions. She is angered and deliberately tries to harm Elizabeth. Then she delivers a stern accounting for her patient's silence, as a rejection of her femininity, her marriage, and especially of her son. This scene is portrayed twice--once with the camera on the nurse; once with the camera on the patient. The irritated husband comes for his wife, they return to the city, where Elizabeth's future is ambiguous. But at the completion of their relationship the nurse has grown in wisdom and confidence.