Private investigator Miles Bredon is spending a weekend with his wife, Angela, at the Halliford’s country house. The occasion is a singularly ill-assorted, and ill-fated, house party and Miles soon wishes he hadn’t bothered. Myrtle Halliford cajoles her guests into joining in with an "eloping game", which involves chasing cars across the countryside at night; but the following morning, the body of one of the guests - a man of influence and affluence - is discovered in the silo....
Was his death an accident caused by fumes of poisonous gas; or was it suicide? Before long, Inspector Leyland of Scotland Yard turns up, incognito, to help Miles and Angela solve the mystery.