The novel begins with a description of a car accident that introduces the theme of grief. It is clear that Finny will not live to the end of the novel, and that Autumn feels a deep sense of loss. Finny’s fate is not discussed again until later in the novel. However, a different kind of grief still influences Autumn’s thoughts and actions throughout, beginning with the revelation that Autumn and Finny, while best friends from birth to middle school, are beginning high school as virtual strangers. As Autumn observes Finny and his girlfriend Sylvie at the bus stop, she reminisces on their shared past, infusing the story with her mourning for their friendship. This continues as the novel progresses, with Autumn often reflecting on how things might be different if she and Finny were still friends.

At the beginning of high school, Autumn begins new relationships, surrounding herself with a new group of friends that don’t include Finny and their previously shared friends, and starts a relationship with a new boyfriend. Despite appearing to move on, Autumn continues to reflect on her relationship with Finny. Autumn and Finny also find themselves thrown together because their mothers are best friends. Autumn grieves as she recalls how easy the now-strained relationship once was between she and Finny.