SPOILER ALERT: the following article contains massive spoilers, including the ending. If you have not yet seen the movie, proceed at your own risk, or better, come back to this article later!
SPOILERS AHEAD
The Toolbox Killer Plot Summary and Synopsis
Known as “The Toolbox Killer,” Lawrence Bittaker, alongside his partner Roy Norris, committed heinous acts. Bittaker remained silent about his crimes for 40 years until he met criminologist Laura Brand. Over the course of five years, Brand recorded her many conversations with Bittaker as he spoke from death row about his methods and motives, providing unique insights into the mind of a criminal sadist.
Source: Wikipedia (CC BY-SA 3.0).