In this eerie study of what drives (or allows) people to kill in a team setting, even when they had no criminal history on their own, Furio's personal correspondence and telephone conversations with death-row inmates lend immediacy to the analysis of the phenomenon of the "deadly duo." The unthinkable crimes sketched in this book show that it is just as chancy to accept a ride offered by a couple as it is to hop into a car driven by a single male. Simply stated, couples or groups that kill usually have perverted tendencies as individuals, but it is only when they come together that their combined personality becomes lethal. How does it happen, and what can be done to prevent it? What are the differences between killers who act on their own, and those who prefer to take a partner? What goes through the partners' minds, years later, when they reflect on what they've done?