Cathryn, Susannah York a wealthy children's author living in a London home, is jolted one night by a series of disturbing phone calls. A mocking female voice insinuates that her husband, Hugh, is having an affair. When Hugh returns, he tries to comfort her, but Cathryn is confronted by a figure who seems to be his double, only to watch this visitor morph back into Hugh. The encounter leaves her shaken and increasingly convinced that unseen forces are invading her life, destabilizing both her marriage and her grip on reality.
Seeking respite, the weary couple escape to an isolated cottage in the Irish countryside. Cathryn hopes the quiet will let her finish her book and shoot illustrations, yet the nightmare follows her. As they settle in, she hears her name whispered and sees apparitions that blur the line between the living and the dead. One lunchtime, she watches Hugh pass through the kitchen and transform into René, her late lover, a figure who continues to speak to her and haunt the rooms they share. The boundary between friend, lover, and husband becomes a shifting mirage that Cathryn cannot quite trust.
The tension deepens when Marcel, the neighbor and ex-lover, arrives with his adolescent daughter Susannah Cathryn Harrison for a visit. Cathryn finds herself slipping between reality and fantasy as the men—Hugh, René, and Marcel—seem to interchange before her eyes. René taunts her, handing her a shotgun and urging her to kill him if she truly wants him gone; in a confrontation that turns deadly, she shoots him in the abdomen. Susannah, startled by the scene, discovers Cathryn standing over the ruined camera and bones of a life she thought she understood, insisting the gun fired by accident as she moved it.
Seeking solace, Cathryn wanders to a nearby waterfall, a place where her doppelgänger appears with unsettling regularity. She returns to the cottage to find Marcel waiting inside and soon learns the shocking truth: the old pattern repeats itself, and Marcel is killed in a brutal moment when Cathryn stabs him with a kitchen knife. An elderly manwalking his dog passes by, and Cathryn invites him in for coffee, even as the living room seems to replay with Marcel’s corpse. The old man declines and leaves, while Susannah later visits and hints that Marcel was not home when she woke, deepening Cathryn’s anxiety that she may have killed Marcel.
That night, Susannah remarks that she will grow to be just like Cathryn, and the two share a quiet tea before Cathryn drives Susannah home. On a desolate stretch of road, Cathryn sees her doppelgänger again, trying to signal for a ride. When she returns to the house, both René and Marcel’s bodies have reappeared in the living room. Cathryn drives away from the cottage, but the encounter with the spectral double continues to haunt her. At a bend in the road, the doppelgänger pleads to be let into the car, and the two women speak in unison before Cathryn rams the car into the cliff, sending her doppelgänger plummeting into the waterfall below.
Back in London, Cathryn steps into the shower, only to have the bathroom door swing open. The doppelgänger enters, and Cathryn screams, “I killed you,” while the figure calmly retorts, “Not me.” The final image reveals Hugh’s body lying at the bottom of the falls, implying that the person Cathryn thought she had defeated in the car was the man she believed she had saved—leaving the truth of what happened on that stormy night tangled in illusion and memory.
- Marcel Bozzuffi as René, Marcel Bozzuffi
- René Auberjonois as Hugh, René Auberjonois
- Susannah York as Cathryn, Susannah York
- Barbara Baxley as Voice On Telephone (uncredited), Barbara Baxley
- Hugh Millais as Marcel, Hugh Millais
- Cathryn Harrison as Susannah, Cathryn Harrison
- John Morley as The Old Man, John Morley
