Fact-based drama starring David Tennant as notorious serial killer Dennis Nilsen. 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 human 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 as many as 15 or 16. 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. Also starring Daniel Mays, Jason Watkins and Barry Ward.