Joest is kidnapped after a rendezvous with his lover Ute Vonhoff; his driver is killed in the attack. A kidnapper likes to humiliate Joest. A renewed attempt to blackmail the family convinces the inspector that Joest is keeping a secret.

Two men break into the Düsseldorf building authority with the help of an employee. When they are surprised by the security guard while taking photos of site plans, they kill him and fake a robbery and murder.

A baffling discovery shakes Ludwigshafen: on the misty banks of the Rhine, a mother and daughter discover the body of a young man - yet when the police arrive, the deceased has vanished. Inspector Lena Odenthal faces a mysterious case, for the man presumed dead had only recently crossed her path as a witness in a drug investigation. As she picks up the trail of a mysterious figure known as "Mother," she has no idea that she is thereby putting her own life at risk…