On a Los Angeles street, Officer Rawlins, a patrolman on his way home from work, stops a man he suspects of being a burglar and is shot and mortally wounded. The minor clues lead nowhere. Two police detectives, Sergeants Marty Brennan (Scott Brady) and Chuck Jones (James Cardwell (actor)), are assigned to catch the killer, Roy Morgan (Richard Basehart), a brilliant mystery man with no known criminal past, who is hiding in a Hollywood bungalow and listening to police calls on his custom radio in an attempt to avoid capture. His only relationship is with his little dog.