As a wild party rages on, loner Dagmar Brink (Eva Henning) plays the piano. A reveller requests a specific song. She stops abruptly. The next morning, the housekeeper finds Dagmar's body hanging from the ceiling. Hearing what has happened, a curious neighbour - writer Anders Wikner (Ulf Palme) - gets to work investigating what led to such an event. With pitch-perfect pacing, sharp dialogue and atmospheric cinematography, Hasse Ekman's masterful mystery was described by Ingmar Bergman as one of the greatest Swedish films of all-time.