On 9 February 1983, Detective Chief Inspector Peter Jay is called to the leafy North London address of 23 Cranley Gardens, where he discovers the drains clogged with rotting flesh and bones. But the extent of this grisly discovery only becomes apparent when the culprit returns from work. Dennis Nilsen, a meek man, freely admits to the police that it's not just one or two bodies but "15 or 16, I think". How had they allowed this to happen under their noses for five years, and what had driven this seemingly ordinary civil servant to commit such atrocities?As the police try to secure a conviction and identify the victims from scant DNA evidence, biographer Brian Masters attempts to understand why. A game of chess with ‘Des' begins, and while Brian may be exhilarated by his newest subject, he's unaware what this new obsession could do to his life.