When Dr. Cyprus Keller lines up to start the Pittsburgh Marathon, he knows someone is going to diefor the simple reason that he's going to kill him. Keller, a university professor and former policeman, is an expert in criminology. But when he finds himself both a murder suspect and a possible victim, he begins to ask questions that somebody does not want answered. In the 26.2-mile race, Keller recounts how he found himself involved in killings that have shocked the city, while he pursuesliterallyhis prey: the man who is behind it all.