"The Moonstone" is a detective novel that revolves around a large, valuable yellow diamond that was stolen from an Indian temple and is now in England. The diamond is bequeathed to a young woman on her eighteenth birthday, but is stolen that same night. The novel follows the investigation of the theft, which is complicated by a series of confusing events and false leads. The resolution involves the unraveling of a tangled web of deception, crime, and colonial guilt.

In this fantasy novel, two children staying in a rural English village stumble upon an ancient magical stone that is the key to a struggle between good and evil forces. As they are drawn into a world of myth and legend, they encounter a host of magical creatures and characters from local folklore. With the help of a wizard, the children must navigate treacherous landscapes and battle dark forces to keep the powerful stone out of the hands of the malevolent Morrigan and her minions, who seek to use it to dominate both the magical and human worlds. The children's courage, loyalty, and resourcefulness are tested as they fight to protect the stone and maintain the balance between light and darkness.