An exquisitely designed silver coffee-pot in the shape of a locomotive is on its way to Cardiff in the care of the young, talented silversmith, Hugh Kellow. It has been commissioned by wealthy ironmaster Clifford Tomkins for his acquisitive wife. When the coffee-pot is stolen and a gruesome murder committed, Winifred Tomkins is distraught. Caring little for the dead silversmith, all she thinks about is her missing treasure. Inspector Colbeck and Sergeant Leeming are summoned to Wales, where the situation is further complicated by the arrival of a famous theatre company, and revelations of illicit liaisons in local high society...