Los Angeles resident Tom Keegan becomes an unwitting witness to a bank robbery, but remembers absolutely nothing about what happened. Forensic psychiatrist Paul Drummond interrogates him under hypnosis, and in a state of trance, Keegan talks about the terrible visions that have haunted him for twenty years. A Vietnam veteran, Keegan has no memories of the war itself or his participation in it. Seriously suspecting that someone has deliberately invaded his patient's mind and severely violated his memory, Drummond decides to conduct a more in-depth examination. High officials of the CIA are in danger of being exposed, and they will stop at nothing to ensure that the sinister secret dies along with those who learn of its existence...