One night at a pharmacy in Des Plaines, IL, a 15-year-old named Chris Gant mysteriously disappears after being seen talking with a heavy-set contractor named John Wayne Gacy (Dennehy).
The boy's parents immediately call in the Des Plaines police, led by Lt. Joe Kozenczak (Riley) who investigates Gacy's background to find out that the contractor had a history of assaulting young men.
A search warrant is obtained and evidence from the Gacy house reveals the contractor's ties to several missing boys.
Gacy is put under surveillance but strikes back with a lawsuit.
Eventually a second warrant is obtained, and something more frightening is found - there are bodies buried all over the property!
Gacy is charged with 33 counts of first-degree murder.
This is the true story of how the worst serial murderer in the history of the United States to that time was eventually brought to justice, and how the methods used to apprehend him became the model for law enforcement across the country in detecting & apprehending serial killers.