Gaia Gill is the last person in the world anyone would expect to go missing. Beautiful, athletic, and recently accepted to a prestigious college, she has everything to look forward to—but the night of her going-away party at the Moon Mountain ski resort, she disappears.Gaia's younger sister Esme is supposed to be flying back to England with her family after the party, but she can't leave with Gaia missing—especially because nobody remembers Gaia leaving the party. Or if they