Dr. Kimberly Powell, a Ph.D. in neuropsychology, works in a research lab trying to understand the roots of violence by stimulating the brains of aggressive rats to reduce their savagery. Her successes lead to phase I safety trials in volunteers and prisoners, and then to phase II and III studies in patients. Soon it becomes clear that Kim's brain stimulating techniques, besides controlling aggression, offer the potential to cure a number of medical...