The story follows Isabel “Belly” Conklin as she turns sixteen and reunites with Susannah Fisher and her sons, Jeremiah and Conrad, the latter of whom Belly has secretly loved since childhood. Previous summers have shaped their relationships, and Belly now navigates the challenges of growing up and experiencing first love. Spending summers at Cousins Beach, she always felt like an outsider, being the youngest and only girl. But this summer is different—Conrad and Jeremiah finally notice how much she’s changed. Belly senses this will be an unforgettable summer, full of new experiences and inevitable changes.