In the Pittsburgh Marathon, 18,000 people from all over the world will participate. Some 9,500 will run a half marathon, 4,000 will run in relays, while 4,500 participants will attempt the full 26.2 miles. Over two hundred will quit before it's over. More than one hundred will be injured and require medical treatment. And one man is going to be murdered.

When Dr. Cyprus Keller lines up to start the race, he knows who is going to die—for the simple reason that he's going to kill him.

Keller, a university professor of criminology at Three Rivers University and a former police officer, is an expert in criminal behavior and victimology. However, when one of his female students is murdered and his graduate assistant attempts to kill him, Keller finds himself swinging frantically back and forth between being a suspect and a victim. When the police assign a motive to the crimes that Keller knows cannot be true, he begins to ask questions that somebody out there does not want answered.

In the course of 26.2 miles, Keller recounts how he found himself encircled by a series of killings that have shocked the city, while he pursues—literally—his prey: the man who is behind it all.