Pilhau, the brewery owner who had been reported missing, is found hanged. T. believes the kidnapping was a perfidious ploy staged by the egocentric man. But his death was certainly not planned. The vast amounts of Pilhaus' blood that were secured after his disappearance, even though the body showed no wounds, also point to the staging.

Chief Inspector Rabe is suspected of taking revenge on the reckless driver who ran over his daughter, shooting two innocent people in the process. Rabe's last hope: Professor T. The two victims, the owner of a fine dining restaurant and drug lord Oppermann and his employee Clara Reuter, quickly lead investigators to her husband, Thomas Reuter.

Professor T. challenges his students to commit the perfect murder—in theory. But theory catches up with practice when the police are confronted with a mysterious murder. After returning from vacation, the Krüger family finds the waterlogged corpse of a Vietnamese man in their bathtub. The case is initially a mystery, the man's identity unknown, and the police have no leads.