On February 9th 1983 Dennis Nilsen was arrested at his Muswell Hill home, after human remains had been identified as the cause of blocked drains. ‘Are we talking about 1 body or 2′, a detective asked. Nilsen replied ’15 or 16, since 1978. I’ll tell you everything’. Within days he had confessed to 15 gruesome murders over a period of 4 years. His victims, all young homosexual men, had never been missed. Brian Masters, with Nilsen’s full cooperation, has produced a study of a murderer’s mind which is unique of its kind.