A drenched vehicle covered in mud on the bank of the Havel. Did someone just illegally dispose of their scrap metal? Hardly, as Wolf and Fahri find the driver still inside the car - dead! The situation is far too strange to be classed as a traffic accident: who rams a car, forces it into the water, accepting the fact that the driver - barkeeper Markus Rost - drowns, then simply pulls the vehicle ashore, together with the corpse, with the help of a winch? The Berlin Water Police are faced with a mystery. Elke, the mother of Markus, and resolute landlady of the Rabenklause pub, describes her son as the personification of an angel. But Elke's friend Bülent informs the police that Markus, once his work shift was over, tended to pick up inebriated women from the pub and take them home, where he shamelessly took advantage of their helplessness. During the investigation, the WaPo team discovers that some time ago, Paula's old girlfriend Isa was one of Marcus' victims. He apparently kept her fettered for several days in his apartment. Isa's boyfriend David Pietsch beat him up to avenge the abuse his girlfriend suffered. Was this just an initial warning? When the investigation reveals that Markus Rost had once again picked up a woman on the evening of his death, a race against time is underway. Will the WaPo be able to find the unknown victim in time? And who killed Markus?