A dead man lies in a Duisburg bus - apparently the accidental victim of a stabbing. The murdered man was the owner of a dance studio that he ran together with his wife, Manuela Prinz.

The investigation reveals that the perpetrator is a Thai. But when the detectives track him down, they find another body. Everything indicates that the Thai committed suicide. Schimanski suspects that the aloof Manuela is not telling him everything she knows. But suddenly it is she who asks him for help: her husband's "business friends" have contacted her and threatened her life if she is not willing to secure further "deliveries".