Young. White. High IQ. Middle-class family. Naval rating. A portrait of a yuppie success story? No. A portrait of child killer, Derek Ernest Percy. In this definitive, graphically chilling account of Percy's life, Debi Marshall applies her investigative journalism skills to a forensic examination of the crimes, the man and his modus operandi. Informed by exclusive material never before seen - poignant and insightful interviews with Percy's mother, victims' families, psychiatrists, police officers and former colleagues - Marshall also takes us on her personal journey as she seeks to unravel the truth about the monster whose lonely, idiosyncratic character has deceived the best psychiatric minds for 40 years. Is Derek Percy responsible for Australia's worst unsolved child abductions and murders? Is he mad - or just bad?