DI Wesley Peterson is called to an unusual crime scene. The victim, Charles Marrick, has been murdered, his body drained of blood. Described by those who knew him as "evil", it seems there won't be a shortage of suspects. But when a popular local vet is murdered in an identical fashion, Wesley wonders what the two men could possibly have in common.
Meanwhile, Wesley's archaeologist friend Neil Watson is alarmed when he starts getting disturbing anonymous letters about macabre events at a medieval abbey. Neil fears that the author of the letters is the killer that Wesley is tracking. As the sinister truth unfolds, both Wesley and Neil are forced to face shocking revelations.