Harry Benson (Segal) is a brilliant computer scientist who suffers from seizures that induce blackouts and violent behaviour. Undergoing experimental surgery, electrodes are implanted in his brain to detect oncoming seizures and stop them with an electrical impulse. But the pleasure centre of his brain becomes addicted to the stimulus, triggering seizures at shorter and shorter intervals. If they become continuous the blackouts will be permanent, and Benson a homicidal killer.