It is an extraordinary, but well-documented phenomenon—two people, who seem relatively harmless alone, team up, and the results are terrifyingly explosive. Such unfortunate unions have been behind some of the most shocking news stories of recent years. But what is it that makes couples like Myra Hindley and Ian Brady follow such a twisted path of sociopathic violence? He offers a rare, if uncomfortable, insight into the truth behind the headlines and exposes some of the most cold-blooded killers that the world has ever seen. Included are some well known cases, including the sickening murders committed by Fred and Rose West at their very own house of horror, 25 Cromwell Street. Other cases are more obscure, but equally fascinating, such as the story of Cynthia Coffman and James Gregory Marlow whose relationship led to three brutal murders. Every one of the 22 cases of shared madness is a uniquely revealing study, making this a must-read for anyone with an interest in true crime and criminal psychology.