The owner of a "sauna club" is found murdered in his car. An employee's teenage son has a history of condemning the club and especially his mother's involvement, but Derrick knows the case is seldom that simple.
A young prostitute is found strangled in a park. The only lead left by the perpetrator is a hat lying on the ground. The scent hound leads the cops to a house where all the tenants appear a bit strange.