Patricia Wentworth

''The Coldstone'' by Patricia Wentworth, first published in 1930, public domain. When young Anthony Colstone inherits Stonegate from his grandfather's cousin, he hardly expected to be haunted by death. Why had Sir Jervis wanted him to promise never to move the ancient megalithic stones and why did no one even know how many there were? Surely old Susan Bowyer knew--- she was nearly one hundred and she knew everything about the village.
And perhaps her great-granddaughter, young Susan, knew something, at one moment a shy village maid, the next a sophisticated young woman. Then one night a wall in the queer old library moved and Anthony found himself on the trail of a mystery that exceeded his wildest imagining. Mystery, adventure, and romance combine in Miss Wentworth's most sparkling manner.