Robert Gribbin stars as Howard, a dry cleaning delivery van driver and pampered mama's boy who goes over the deep end in this violent exploitation thriller. Howard is mild-mannered and slightly simple-minded, with a habit of picking up teenage hitchhikers while driving his delivery routes. Sometimes the girls admit to being runaways, and if they claim to hate their mothers it drives Howard into a violent frenzy; his sister ran away from home years ago and was never heard from again, causing his desperate, addled mother to tighten her hold on him. Howard never remembers raping his victims or strangling them with wire coat hangers, though his boss does notice missed deliveries and late arrivals. He becomes increasingly careless during these violent fits, strewing clues that the police are unable to piece together. The crime spree is investigated by Captain Shaw (Russell Johnson), who hopes that this "mental case" doesn't turn out to be another Zodiac Killer. Howard starts feeling sick and uneasy but can't understand why, suffering nightmares and headaches. His job is in jeopardy and the stress overwhelms him, so when he picks up an 11-year-old girl alone on the interstate, he makes a final mistake.