Avery is a local resident of Littleport who works as a property manager for the wealthy Loman family. Having lost her parents in a car accident and her grandmother shortly after, she clings to the stability the Lomans provide. She actively searches for answers surrounding the recent, suspicious death of her best friend, Sadie. Her determination frequently pushes her to question the official police rulings.

Sadie is a wealthy summer resident from Connecticut who dies under mysterious circumstances near Breaker Beach. She projects a bright, optimistic exterior that conceals the immense pressure she feels from her family's expectations. Her death, initially ruled a suicide, serves as the catalyst for the events of the novel.

Parker is Sadie's older brother and heir to the Loman family business. He behaves recklessly and largely ignores the consequences of his actions. His interactions with Avery are tense but layered with mutual attraction.

Detective Collins serves on the Littleport police force and acts as the lead investigator for Sadie's death. He previously responded to the car accident that killed Avery's parents years ago. He maintains a firm, authoritative stance when questioning locals.

Luciana visits Littleport as Parker's girlfriend. She works as an occupational therapist and observes the local dynamics with a critical eye. She openly distrusts Avery, feeling threatened by Avery's deeply rooted history with the Loman family.

Connor works at the local docks and previously dated Avery. He maintains a quiet life in Littleport but occasionally interacts with the wealthy summer residents. Rumors circulate about a private connection between him and Sadie.

Faith grew up in Littleport and was once Avery's closest friend. Her parents operate a struggling bed and breakfast that competes with the Lomans' rental monopoly. She harbors deep resentment toward Avery over a past falling-out.

Grant is the wealthy patriarch of the Loman family. He owns numerous rental properties in Littleport and employs Avery to manage them. He expects absolute loyalty from his workers and his children.

Bianca is the matriarch of the Loman family. Following her daughter's death, she channels her grief into organizing a suicide prevention foundation. She struggles with her loss and frequently clashes with Avery over the details of Sadie's final days.

Greg lives in Littleport and harbors a long-standing, unrequited crush on Sadie. He actively dislikes Avery, viewing her as an intruder in Sadie's upper-class social circle.

Erica assists the committee planning a memorial dedication for Sadie. She previously worked at a party where Avery and Sadie first met.

Ellie attends the summer-ending Plus-One Party. She accidentally falls into the property's pool when the power goes out unexpectedly, requiring Parker to help her out.