A former astronaut is hired by a detective agency to help in an investigation of a case of mysterious deaths. Several victims became mad and committed suicide during their vacation in various Naples spas, apparently without reason. Due to certain similarities in the circumstances of the deaths the case is assumed to be a serial murder by poisoning, although it is never certain what (if any) real connection exists between the victims.

During the investigation, it becomes apparent that certain innocent chemicals can be combined into a strong depressor, a kind of chemical weapon. The hero experiences its effects, but his training helps him to survive and solve the case. He discovers the industrial sources of the chemicals, and demonstrates how random chance chemical reactions led to the string of deaths.