Since the end of the nineteenth century, the Oakley family of Bamford, England, has lived in the shadow of tragedy. In 1889, Cora Oakley died by inhaling a poisonous gas in her sleep, and her husband William was put on trial for the murder. Although the case was dismissed, Oakley's reputation was ruined, and he fled the country, never to be heard from again.

Over a hundred years later, the only remaining members of the Oakley family are two elderly sisters living in Bamford, who exist in poverty in their rambling ancestral home, Fourways. Unable to maintain their mansion, the sisters have decided to sell the house and live comfortably on the proceeds. But a young Polish man named Jan appears, claiming to be William Oakley's great-grandson and brandishing what he alleges is Oakley's will, which entitles him to half the profits from the sale. The sisters panic, knowing that, although Jan's claims don't stand up, a court case could drag on for years, and time is not on their side. When Jan is found dead, poisoned by the same substance used to kill his great-grandmother so many years ago, it seems that murder has returned to haunt the Oakley family once again, and Superintendent Markby must unravel two mysteries, one from a hundred years ago, to find the killer.