Dr. Arne Lundell, a brilliant young assistant in a mental hospital, is accused of plagiarising his thesis from a work published simultaneously by his superior, Professor Zander.
The film proper begins with the return of Lundell's wife, Marianne, to their flat. Finding her husband in a state of uncomprehending despair, she does her best to console him. Then they hear on a radio news bulletin the report of Zander's death by suicide; and later (...) that the suicide is in fact murder and that Lundell may be accused since he is known to have threatened Zander.
Gradually the true story is told between husband and wife after he discovers (a letter pushed under the door) that she had formerly been Zander's mistress. It transpires that Zander had threatened to wreck her marriage unless Marianne secretly passed him her husband's thesis, which she did, chapter by chapter as it was written; and had then proposed to wreck Lundell's career unless Marianne divorced her husband and came to him, whereupon she shot him.
Moved by these revelations, Lundell urges Marianne to make her escape abroad while he stays to shoulder the blame; but she poisons herself, and he chooses to die with her. (Excerpt from The Cinema of Carl Dreyer by Tom Milne, published 1971).