Dr. Brock Williams is a psychologist in Boulder, Colorado where he treats a variety of patients. A religious killer is at large in the area leaving a Bible page at each crime scene with the victim's "sin" highlighted. It seems a coincidence initially that each victim is Brock's patient but suspicion rises when more and more patients are killed. The pressure builds when it's discovered the "sin" each victim was killed for was also the victim's presenting problem in therapy. When Brock's fingerprints are found at a murder scene, the authorities begin to zero in on him as their primary suspect. Brock realizes he must catch the killer to save his patients from further harm and to avoid prosecution himself. Attempting to unravel the mystery leads him deep into a psychological maze and a trap carefully set by the killer, one that implicates him in the murders and could take his life.