When Rachel Verrinder inherits the Moonstone -- a huge and accursed yellow diamond, a diamond stolen generations ago from an Indian shrine -- from John Herncastle she has no idea what evil waits for her. Herncastle -- a distant relation, and one spitefully alienated from her immediate family -- intended the bequest as a sinister form of revenge. Revenge indeed: Herncastle, we learn, acquired the Moonstone by means of murder and theft, and knew full well that the jewel would bring dreadful luck upon her.