A man is spiked by bamboo when he goes swimming in a lake near Kiel. Borowski and Sarah Brandt consider the possibility of a madman finding his victims at random. Or was it some sort of obscure punishment? The victim's girlfriend seems to play a deciding role. Ina Santamaria uses an Internet chatroom to date men for casual sex and the dead man was one of her lovers. Then Borowski receives unexpected assistance from the Swedish police. His old friend inspector Enberg is investigating in a rabies case, which brings him to Schleswig-Holstein. The two cases seem to be linked; driven by a sinister lust for revenge, the murderer evidently infects his victims with rabies before spiking them to death. Another murder then surpasses all prior events.