In late 1923 Berlin, Abel Rosenberg, David Carradine, an unemployed alcoholic and former trapeze artist, struggles to cope with the grinding hardships of post-war Germany. After learning of his brother Max's suicide, he is offered money by his old circus boss to return to the act, but he declines, convinced he won't measure up without Max. He then meets Max's wife, Manuela Rosenberg Liv Ullmann, to break the news, though he cannot provide a clear explanation beyond a fragment from Max's note mentioning "poisoning."
Seeking solace in drink, Abel spends a night at Manuela's house. When she leaves for work, he steals from her to buy more alcohol. Shortly thereafter, police bring him to identify several bodies found near his home, and suspicion quickly falls on him. He attempts to escape but is recaptured.
Manuela visits Abel in the hospital, revealing that all her money is gone. Abel is released for lack of evidence and returns home, only to face eviction because they are not married. Manuela confesses that she is a prostitute, having crafted an ordinary office job to hide her shame.
As November unfolds with armed confrontations between extremist parties looming, Abel and Manuela live on the outskirts of Berlin, constantly fearing for their safety. One morning, Abel secretly follows Manuela and discovers she has been going to church. She confides in a priest, James Whitmore, expressing guilt over her husband's death and the fear consuming their lives.
Abel learns that Manuela secured their apartment by providing sexual favors to the brothel's owner. Initially repulsed, he later returns to her, and they share a passionate kiss. Their fragile closeness is shattered when soldiers overrun the brothel and kill the owner.
Abel finds a job as a file clerk in a hospital, while Manuela works at the clinic. They live in an apartment surrounded by abandoned buildings.
One night, Abel discovers files detailing inhumane experiments conducted on patients at the hospital. Overwhelmed by fear, he withdraws from intimacy, and Manuela experiences extreme mood swings. After a drunken episode and a later encounter with a prostitute, Abel returns home to find Manuela dead and cameras scattered in the apartment.
Fleeing the scene, Abel ends up in an abandoned industrial building and fights off an unknown attacker in an elevator, decapitating him. Returning to the hospital, he confronts the doctor about the experiments. The doctor claims the subjects were volunteers driven by desperation and shows footage of Max injecting himself with a serum that ultimately led to his suicide. The doctor justifies the experiments as a step toward benefiting mankind, and then commits suicide with cyanide as the police arrive.
Abel is placed in a psychiatric ward to recover. The chief of police informs him that the circus has offered his old job, and he is forced to accept. He escapes from police custody on the way to the train station, and a voice-over suggests that he evades capture and is never seen again.
