On sick leave from Scotland Yard, Inspector Alan Grant is planning a quiet holiday with an old school chum to recover from overwork and mental fatigue. Traveling on the night train to Scotland, however, Grant stumbles upon a dead man and a cryptic poem about the stones that walk and the singing sand, which send him off on a fascinating search into the verse s meaning and the identity of the deceased. Grant needs just this sort of casual inquiry to quiet his jangling nerves, despite his doctor s orders. But what begins as a leisurely pastime eventually turns into a full-blown investigation that leads Grant to discover not only the key to the poem but the truth about a most diabolical murder.