Crowner John is summoned to Dartmoor after a respected mine overseer is murdered. The victim worked for wealthy tin owner Walter Knapman, and the first explanation is commercial sabotage, but the independent customs of the tinners make witnesses hostile to outside officials and complicate the inquest.
When Knapman disappears and a decapitated body is found, rival mine owners, an apparently indifferent wife and men angered by Norman rule all come under suspicion. John’s personal difficulties become secondary when Gwyn is arrested for murder, forcing the coroner to expose the real sequence of deaths before his closest ally is condemned.