When wealthy, impulsive summer girl Margot meets hardworking and steady local girl Thea in the summer of 1967, the unlikely pair become fast friends, working alongside one another in a record store and spending every spare moment together. But after an unspeakable incident on one devastating August night, they don't see one another for ten years...until Margot suddenly reappears in Thea's life, begging for help and harboring more than one dangerous secret. Thea can't bring herself to refuse her beloved friend--but she also knows she can't fully trust her either.

Unfulfilled as a housewife, Thea enjoys the dazzling sense of adventure Margot brings to her life, but will the truth of what happened to them that fateful summer ruin everything? Testing the boundaries of how far she'll go for a friend, Thea is forced to reckon with her uncertain future while trying to decide if some friends are meant to remain in the past.

Set in the dual timelines of 1967 and 1977, All the Summers In Between is at once a mesmerizing portrait of a complex friendship, a delicious glimpse into a bygone Hamptons, and a powerful coming-of-age for two young women during a transformative era.