A precocious thirteen-year-old girl navigates the shifting dynamics of her family and their summer lake house in 1965. Franny Wahl feels overlooked by her parents, Harold and Peg, who are preoccupied with their older daughters, Rosamund and Martie, and the arrival of summer visitors. Rosamund is attracting the attention of a former suitor of her mother's, while Martie hosts constant parties. As Franny seeks her own experiences, her actions inadvertently disrupt the established order of the Wahl family, revealing hidden tensions and desires within their seemingly idyllic summer retreat.

The premise sets up a coming-of-age story centered on a young protagonist observing and influencing her family during a pivotal summer. The narrative framework suggests a focus on internal family dynamics and the subtle shifts in relationships as characters mature and external influences arrive. The description points to a character-driven plot where adolescent discovery intersects with adult concerns. The novel likely explores themes of identity, family expectations, and the loss of innocence within a specific historical and geographical setting.