Gloucester Abbey becomes paralysed with fear on the discovery of the missing monk, Brother Nicholas, with his throat cut. Domesday Commissioners arrive to settle a land dispute but are greeted by the confusion and a sinister threatening presence. The ordered calm of Gloucester Abbey is shattered by the murder of one of its monks. The Abbot, ill-equipped to deal with such a heinous crime, is stunned by the Sheriff's belief that one of the monks is guilty. This is the confusion that that greets the two Domesday Comminisioners, Ralph Delchard and Gervase Bret, as they are welcomed into the town. Eager to resolve the mystery, they begin their own investigations but find the killing is merely a sign of a sinister presence which threatens the whole community and which must be stopped.