Why do people kill together? How do the evil thoughts of one become the evil deeds of two? We probe the physiology of love and the power of authority as we unravel the motive and methods of some of the most notorious accomplice killers. From Ian Brady and Myra Hindley, Britain's "Moors Murderers," who brutally murdered five children, to Charles Lake and Leonard Ng, who tried to create a colony of sex slaves, the secrets of these evil partnerships are revealed.