What happens when delusion, obsession, and jealousy collide? Violent stalkers are among the most terrifying criminals, preying on victims with a chilling determination. What can explain this relentless drive, and what triggers violence in the mind of a stalker? Neuro-psychology is explored on the cases of four notorious stalkers, to provide insights into the science of deadly obsession. Robert Bardo, killer of television actress Rebecca Schaeffer, speaks from prison to give Dr. Stone his first-person account of the crime.