Plot: Based on a true story. He called himself the Angel of Death. But when the police discovered that he was involved with over 40 deaths, his name soon became Killer Nurse. In the beginning it was his story against theirs. Soon he gave up his version of the events and admitted to killing 43 patients in his care at the St. Mary's Hospital. Charles Cullen also became one of the most notorious serial killers in the history of the US.