Fascinated by the human brain and its capacity for ruthlessness, psychiatrist Dr. Dorothy Otnow Lewis has spent her life investigating the interior lives of violent people. With each case, she came closer to developing a unified field theory of what makes a killer. Along the way - steering away from the conventional wisdom of her colleagues - she explored the world of multiple personality disorder.
British documentarian Nick Broomfield creates a follow-up piece to his 1992 documentary of the serial killer Aileen Wuornos, a highway prostitute who was convicted of killing six men in Florida between 1989 and 1990. Interviewing an increasingly mentally unstable Wuornos, Broomfield captures the distorted mind of a murderer whom the state of Florida deems of sound mind -- and therefore fit to execute. Throughout the film, Broomfield includes footage of his testimony at Wuornos' trial.