Aidan and Sarah cooper have no idea what they're getting into one afternoon when they discover a mysterious coded document in a secret compartment of an antique English desk their father recently bought at an auction. Something about the document seems familiar to Sarah, and that night she realizes what it is: the document seems to be referring to some books she has read—the Starcatchers series, about the origin of Peter Pan. But how could that be? The document seems far older than the books. And of course, the books are just stories.

Curious, Sarah and Aidan begin to decipher the mysterious document. At first it's a game—unraveling the mystery piece by piece, each piece leading them to a new, deeper puzzle. But soon the game turns strange—and scary. Pursued by a being that can take any form and will stop at nothing to get what it wants from them, Aidan and Sarah embark on a desperate, thrilling quest for help—a quest that leads them to some unforgettable people in some unlikely places, including one that's not supposed to exist at all.