On 9th February 1983, a grisly discovery alerts Hornsey Police to a serial killer, operating under their noses for years. DCI Peter Jay is stunned when meek Dennis 'Des' Nilsen freely admits to killing multiple men without knowing why.
When the police are called to a blocked drain, they discover that the drains are blocked with bones and rotting flesh. They talk with the resident of the top floor flat. He is a meek civil servant, Dennis Nilsen. Des to his friends and he confesses to the murders. How did the police allow this to happen over the previous five years.