When a letter arrives at Tradmouth police station addressed to a DCI Norbert it causes quite a stir. For though DCI Norbert has long since moved on, the letter claims to have evidence that the man convicted of murdering the Rev. Shipbourne, Vicar of Belsham, during a robbery in 1991, is innocent. Despite having a full caseload, DI Wesley Peterson is forced to at least follow up on the claims. Meanwhile archaeologist Neil Watson is excavating a site in Pest Field. He discovers a mass grave that leads him to conclude that the site is one of an ancient medieval plague pit. But, more disturbing, is the discovery that the grave is home to a more recent resident
