No matter what the world throws her way, at least Ruthie Beamish has the house. Located by the sea in a quiet Long Island village, the house is her nest egg—the retirement account shared with her ex-husband, Mike, and the college fund for their teenage daughter, Jem. The catch? To afford the house, Ruthie must let it go during the best part of the year.

It’s Memorial Day weekend and the start of what Jem calls “the summer bummer”: the family’s annual exodus to make way for renters. This year, the Hamptons set has arrived. Adeline Clay is elegant and connected—and will never need to worry about money. Before long, she demonstrates an uncanny ability to help herself to Ruthie’s life. Is Adeline just being her fabulous self, or is she out to take what she wants?

When an eccentric billionaire, his wayward daughter, a coterie of social climbers, and Ruthie’s old flame are thrown into the mix, the entire town finds itself on the verge of tumultuous change. But as Ruthie loses her grasp on her job, her home, and her family, she discovers a new talent for pushing back. By the end of one unhinged, unforgettable summer, nothing will be the same—least of all Ruthie.