While Barnaby is away on holiday his replacement, the soon to be retired Ron Pringle, arrests Billie Gurdie for the murder of a tramp who lived in the woods near the village of Upper Marchwood. When Billie's father is also found dead in the same woods some three weeks later, an apparent suicide, Barnaby seriously questions the coincidence. When the post-mortem reveals the second death to also be murder, Barnaby is certain that both murders were committed by the same person.
