Finna's mother is dead. So why is this woman standing on her stoop claiming to be just that? Catriona arrives bearing a gift-a luminous moonstone that holds the secrets to Finna's heritage. What heritage? Catriona insists that the two of them must journey to the castle of the Celtic moon goddess, Arianrhod. Moon goddess? The story Catriona weaves is preposterous. A parallel reality, known as the 'Otherworld', exists next to this one. According to her, this place has no electricity, cars or any other modern conveniences. "The moonstone will show the way," Catriona intones cryptically. Newly...