Description
Mark is a spy who returns home to West Berlin from a mysterious espionage mission to find that his wife, Anna, wants a divorce. She won't say why but insists it's not because she found someone else. Mark reluctantly turns the apartment and custody of their young son, Bob, over to her. After recovering from a destructive drinking spree, he visits the apartment to find Bob alone, unkempt, and neglected. When Anna returns, he stays with Bob, refusing to leave her alone with the child but attempts to make amends. Anna leaves in the middle of the night.
Mark receives a phone call from Anna's lover, Heinrich, telling him that Anna is with him. The next day, Mark meets Bob's teacher, Helen; she inexplicably looks identical to Anna but with green eyes. Mark visits and fights Heinrich, who beats him. Mark then beats Anna at home, after which she flees. The next morning, they have another hysterical argument during which they both cut themselves with an electric knife, Anna on the throat and Mark on the arm.
Mark hires a private investigator to follow Anna and discovers that she has been keeping a second flat in a derelict apartment building. When the investigator discovers a bizarre tentacled creature in the bedroom, Anna kills him with a broken bottle. The lover of the now-dead detective, Zimmerman, goes to the flat himself, where he finds the creature and his lover's dead body. Anna beats Zimmerman in a rage before stealing his gun and then shooting him to death.
Anna continues her erratic behavior and recounts to Mark a violent miscarriage she suffered in the subway while he was gone. She claims it resulted in a nervous breakdown; during the miscarriage, she oozed blood and fluids from her orifices. Heinrich visits Anna at the second apartment and is shocked to discover the creature in the bedroom, as well as a collection of dismembered body parts in her refrigerator. She attacks him and Heinrich flees, bleeding.
Heinrich calls Mark and begs him to pick him up. Mark stops by Anna's apartment first and discovers the body parts; the creature, however, is gone. Mark meets Heinrich at the bar where he murders him, but stages it as an accidental death in the bathroom stall. He then sets Anna's apartment on fire before fleeing on Heinrich's motorcycle. At home, he finds Anna's friend Margie on the point of death as she emerges from the lift, bleeding from knife wounds. She dies; he drags the body inside where Anna greets him, and the two have sex in the kitchen. Afterward, he makes plans to cover up Margie's death. He then discovers Anna having sex with the creature as she cries "Almost!" over and over again. Heinrich's mother phones Mark asking about her son. When he goes to meet with her, she commits suicide by poisoning herself.
The next day, as Mark wanders the street, his former business associates pressure him to rejoin them. He is evasive and returns to Margie's apartment to find it surrounded by police and his former employers. He stages a distraction, allowing someone, possibly Anna, to sneak away in his car, but he is wounded in the ensuing shootout. Fleeing on the motorbike, he has a horrific accident and races into a building where he is pursued by Anna, the police, and his business associates. Anna reveals the creature, now fully formed as Mark's doppelgänger. Mark raises his gun to shoot it but he and Anna are gunned down by a hail of bullets from the police below. Bloodied and dying, Anna lies atop Mark and uses his gun to shoot herself. She dies in his arms and he jumps to his death through the stairwell. The doppelgänger flees through the roof.
Later, Helen is at the flat babysitting Bob when the doorbell rings. Bob implores her not to open the door, but Helen ignores him. From outside, the sound of sirens, planes, and explosions fill the air. Bob races through the flat into the bathroom, where he floats in the bathtub face-down. The silhouette of Mark's doppelgänger is seen from the frosted glass door. Helen stares, her green eyes shining.
