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.

Beth invites Marcus, the son of Arch's final and most challenging client, to spend the summer with her and her teenage twins Winnie and Garrett, who have mixed reactions to sharing their special summer place with this stranger. Always a place of peace before, Nantucket becomes the scene of roiling emotions and turbulent passions as Marcus, Winnie, and Garrett learn about loss, first love, and betrayal. And when they stumble upon a shocking secret from Beth's past, they must keep it from destroying the family they've been trying so hard to heal.