Inspector DeKok is faced with a grotesque double murder in a well-known Amsterdam hotel. He finds the murder victims looking like macabre wooden harlequins. Inspector DeKok must unravel clues from two unexpected characters: a six-year-old girl who has trouble sleeping, and a respected accountant who seeks DeKok's advice on committing the perfect crime.

But when DeKok meets with the murderer, he tries everything possible to prevent the man from giving himself up to the police…