Answer
In Fritz Lang's classic film "M" (1931), Conrad Veidt portrays a child murderer named Hans Beckert. Beckert suffers from somnambulism, a condition that causes him to perform actions while asleep. This condition plays a crucial role in the film's plot, as Beckert's unconscious actions lead to his eventual capture and downfall. Veidt's haunting performance captures the inner turmoil and desperation of a man tormented by his own subconscious.