This tale is set in the future, where wars have been abolished and people can only give vent to their aggressive instincts through cold-blooded murder. Caroline, an Amazonian-type American, has killed nine men and flees to Rome where she intends to claim her tenth victim, who turns out to be Mastroianni. But he realizes what she is up to and tries to outsmart her. In doing so, they fall passionately in love and end up marrying.