In 1983 Scottish serial killer Dennis Nilsen is arrested after the discovery of human remains which have blocked a drain near his London home.
Cast: David Tennant, Daniel Mays, Jason Watkins, Ron Cook, Barry Ward, Ben Bailey Smith, Bronagh Waugh, Alex Bhat, Jay Simpson, Joel Morris, Gerard Horan, Oscar Garland, Cal MacAninch, Ross Anderson
Reeling from Des' change in plea, Jay and the police throw themselves into proving premeditation. If they can show the court that Des was undoubtedly of sound mind when he committed his crimes, he will go down and never be released.
With limited resources, Jay and the police continue to dig into Nilsen's memories in an effort to identify and convict him for the murder of every one of his victims. But when Des suddenly withdraws his cooperation and stops talking to the police, Jay fears justice will be lost.
On 9 February 1983, Detective Chief Inspector Peter Jay discovers a drain clogged with rotting flesh and bones. The culprit, Dennis Nilsen, freely admits to the police that it's not just one or two bodies, but "15 or 16, I think".