Anastasia (Anna) Cayne is a complicated high school girl with a penchant for riddles and affectionate mind games, who spends much of her time writing obituaries for every living person in town. She is unlike anyone the narrator has ever known, and her energy and enthusiasm explode his quiet universe, revealing a world of Houdini tricks, strange art, covert messages, and ghost stories, although her past remains an even bigger enigma. Even so, he couldn’t be happier.

But a week before Valentine’s Day, Anna disappears, leaving behind nothing except a dress placed neatly near a hole in the frozen river, and a string of unanswered questions.

Determined to find Anna, to comprehend what happened and why, he begins to retrace their past five months together. Soon the fragments of events, conversations, letters—and new messages that continue to arrive—coalesce into haunting and surprising revelations about friends, about family, and especially, about Anna Cayne. And perhaps these revelations will solve the puzzle of Anna’s disappearance, whether it was her own invention or simply another of life’s great mysteries.