A sparkling debut about love, family, and the mysteries of the universe, perfect for fans of Jandy Nelson and Nicola Yoon. Linny has kept a journal of famous disappearances ever since her sister Grace ran away in the middle of the night. Sebastian is an aspiring astrophysicist with a working theory for everything--but the one thing he can't figure out is the identity of his birth father. They haven't met--yet--but...