When coroner Sir John de Wolfe is summoned to investigate the murder of a tin miner, he has little idea how difficult this new investigation will prove to be. The victim worked for the powerful mine owner, Walter Knapman, and the motive seems to be sabotaging Walter’s business. But the tinners have their own laws, and they are none too pleased at Crowner John’s interference. And then Walter Knapman disappears. Only Gwyn, Crowner John’s right-hand man, seems to be of any help—until he’s arrested for murder and put on trial for his life.