Annabelle Hooper is a young mystery writer in search of a story for her future best-selling novel. On a family vacation in Nantucket, she uncovers a 200 year-old mystery that provides Annabelle with the inspiration she's been seeking. Along with local brother-and-sister duo of Jake and Maddi, Annabelle dives into a world of eccentric thieves, psychics, a hazy figure in white, and a mysterious boy named Billy. With an old journal as their guide, the friends follow the clues into adventure.