The story of serial killer Dennis Nilsen, who murdered 15 young men in the 1980s.
| Actor | Role |
|---|---|
| JJohn MorrisonHimself - Presenter / Narrator | Himself - Presenter / Narrator |
| PPeter JayHimself - DCI, Metropolitan Police, 1983 | Himself - DCI, Metropolitan Police, 1983 |
| IIain MacDhùghaillHimself - Criminal Defence Lawyer | Himself - Criminal Defence Lawyer |
| AArchie MacLullichHimself - Consultant Psychologist | Himself - Consultant Psychologist |
| PPàdraig MacAmhlaighHimself - Journalist | Himself - Journalist |
| JJulian BoothHimself - Forensic Psychologist | Himself - Forensic Psychologist |
| BBrian MastersHimself - Author, 'Killing for Company - The Case of Dennis Nilsen' | Himself - Author, 'Killing for Company - The Case of Dennis Nilsen' |
| EElizabeth ScottHerself - Nilsen's Mother | Herself - Nilsen's Mother |
| NNeil McKinvenDennis Nilsen | Dennis Nilsen |
 Ryan FletcherVictim Jamie | Victim Jamie |
 John Paul HurleyDCS Chambers | DCS Chambers |
| LLewis BrownYoung Nilsen | Young Nilsen |
| FFinlay McLeanNilsen's Grandfather | Nilsen's Grandfather |
| NNicholas UnderwoodDCI Peter Jay | DCI Peter Jay |
| AAndy MarjoribanksSolicitor | Solicitor |