March 1987. A Cincinnati coroner autopsies John Powell, a patient who has recently passed away in the city's Drake Memorial Hospital. Powell had been in a coma since a motorcycle accident - his death comes as no surprise. But as the coroner cuts into Powell's stomach he smells burnt almonds. The odour is unmistakable. It's that of the deadly poison Cyanide. The coroner records Powell's death as homicide. Police begin their investigation and receive information regarding an orderly's suspicious behaviour. His name is Donald Harvey. Colleagues call him the Angel of Death due to the number of deaths that occur on his watch. Incredibly, Harvey confesses to killing Powell, claiming he did it out of mercy. Prosecutors charge him with murder but deem it unlikely they'll find evidence that he has killed before. But local news anchor Pat Minarcin is suspicious and takes it upon himself to investigate. Whistle-blowers secure patient records and Harvey's time sheets. Minarcin discovers that Harvey is always on duty when a patients dies. Believing he's uncovered a serial killer, Minarcin calls Harvey's attorney, William Whalen, for comment. Whalen doesn't talk and instead challenges his client to come clean. Harvey admits to killing dozens over an 18-year period and begs his attorney to save him from the executioner. The only option is a plea bargain, admit everything in return for life imprisonment. Prosecutors agree and over the coming months Harvey confesses to over 80 killings making him one of the most prolific serial killers in American history.