As the story opens, we learn that Oscar is missing, presumed dead by suicide, though Meg, as well as Oscar's brother Stevie, won't believe it. Then we are taken back to several months before, and the story tells of Meg's father taking his family to New Zealand with him for six months with work, with Meg bitterly opposed to going. Alternating chapters, like slices of an apple tart, are recounted from Meg's, and then Oscar's, perspective, and gradually reveal how Oscar and Meg's friendship is changed when she does go. A new girl, Paloma, and her mother, move into Meg's house temporarily. With regard to the book's title, Oscar has a heightened sense of when something particular is in the air, and this is when he bakes one of his remarkable apple tarts which improved people's feelings and helped with troubles.