After uprooting her life in the States, Irene Steele has just settled in at the villa on St. John where her husband Russ had been living a double life. But a visit from the FBI shakes her foundations, and Irene once again learns just how little she knew about the man she loved. With help from their friends, Irene and her sons set up their lives while evidence mounts that the helicopter crash that killed Russ may not have been an accident.

Every summer the Newton family retreats to their beloved home on Nantucket for three months of sunshine, cookouts, and bonfires on the beach. But this summer will not be like any other. When Arch Newton, a prominent New York attorney, dies in a plane crash on his way home from a business trip, his beautiful widow, Beth, can barely keep things together. Above all, though, she decides that she must continue the family tradition of going to Nantucket, and at the same time fulfill a promise that Arch made before he died.

Claire has a problem with setting limits. All her life she has taken on every responsibility, assumed every burden, granted every request. Claire wants it all—and in the eyes of her friends, she has it: a devoted husband, four beautiful children, even a successful career as an artist. So when she agrees to chair the committee for Nantucket's social event of the year, she knows she can handle it. Claire can handle anything. But when planning the gala propels her into the orbit of billionaire Lock Dixon, unexpected sparks begin to fly.

Hollis Shaw, creator of the popular food blog, Hungry with Hollis, is shocked when her heart surgeon husband, Matthew, is killed in a one-car accident on a snowy morning. The cracks in Hollis’s perfect life—her strained marriage and her complicated relationship with her daughter, Caroline—grow deeper. So when Hollis hears about something called a “Five-Star Weekend”—one woman organizes a trip for her best friend from each phase of her life: her teenage years, her twenties, her thirties, and midlife—she decides to host her own Five-Star Weekend on Nantucket.

Welcome to the most tumultuous summer of the 20th century. It's 1969, and for the Levin family, the times they are a-changing. Every year, the children have looked forward to spending the summer at their grandmother's historic home in downtown Nantucket. But like so much else in America, nothing is the same.