Harry Benson suffers from violent seizures. So violent that he requires a police guard when entering a Los Angeles psychiatric ward for treatment. Dr Roger McPherson, head of the prestigious NeuroPsychiatric Research Unit is convinced he can cure Benson through a procedure known as a stage three. During this specialised surgery, electrodes, placed deep in Bensons brain send monitored soothing impulses to its pleasure canyons. The operation is a success - until Benson discovers how to get the pulses with increasing frequency. Then he escapes from the hospital and lapses into murderous rampages, becoming a homicidal maniac with a deadly agenda...