Lexi Laney and Clare Hart grew up together swimming in the surf, riding remote bike trails, and having wondrous adventures across picturesque Nantucket. And when it was time to share intimate secrets and let their girlish imaginations run free, they escaped to their magical private hideaway: Moon Shell Beach. But nothing stays the same. With the complicated pressures of adulthood, their intense bond is frayed, hurtful words are exchanged, and Lexi flees Nantucket to a life of luxury while Clare stays behind.