Arianna doesn’t remember the unusual event that happened when she was just four years old. But the crow remembers, and ten years later when Arianna is fourteen he returns to her bedroom window. The visit comes as a surprise to Arianna, but at the same time, she knows the crow is there for a reason, and that there’s something she needs to remember.
Then contrary to what she would normally do, she agrees to accompany her mother Marion and Marion’s best friend Meg on a day trip to Crescent Island. They plan to visit the local museum to see its most recent acquisition, the diary of the late Evelyn Manning. The diary relates the story of Evelyn’s father, a farmer who woke up one morning convinced that the Holy Grail was buried on the family farm.
Intrigued by Evelyn’s strange story, Meg, Marion, and Arianna (the crow ever-present in Arianna’s mind and sometimes in the flesh) set out determined to learn more.