It is Christmas Eve, and 55-year-old Professor Pal Andersen is alone, drinking coffee and cognac in his living room. Lost in thought, he looks out of the window and sees a man strangle a woman in the apartment across the street. Professor Andersen fails to report the crime. The days pass, and he becomes paralysed by indecision. Desperate for respite, the professor sets off to a local sushi bar, only to find himself face to face with the murderer.