After a troubled childhood Dennis Nilsen grew into a lonely and bitter man who struggled to relate to the world around him. After years of loneliness in 1975 Nilsen met David Gallichan and for two years they lived together in a North London garden flat. Whilst Nilsen worked, Gallichan took on a role of playing housekeeper, over time tensions grew between them which later resulted in Galichan leaving Nilsen. This was a trigger which resulted in Nilsen committing one of the worst killing sprees Britain had ever seen.