Brian and Margot Dunne live year-round in Seaside with their daughters, Liz and Evy. The Dunnes run a real estate company, but their future becomes quite precarious when Brian develops a brain tumor. Amidst the chaos and new caretaking responsibilities, Liz still seeks out summer adventure and flirting with a guy she should know better than to pursue. Her younger sister, Evy, works in a candy shop, falls in love with her friend Olivia, and secretly adopts the persona of a middle-aged mom in an online support group, where she discovers her own mother’s most vulnerable confessions. Meanwhile, Margot faces an impossible choice driven by grief, impulse and the ways that small-town life in Seaside has shaped her.