It's August 1952, and seven-year-old Nickel sets off for a day at the seashore with her mother, aunt, and cousin Leroy. Everyone is excited when they reach Chesapeake Bay—everyone except for Leroy, who is recently motherless and frightened of the world around him. Nickel delights in tormenting her cousin, but, as the group lounges on the beach and begins work on a magnificent sand castle, the sisters try to coax him out of his shell by telling stories about their own childhood trips to the shore. However, Nickel's taunting of Leroy escalates, and the family history between her mother and aunt rises to the surface—and then a crab bites Leroy, and they must all come together. Only years later can Nickel see that day for what it truly was—a life-changing lesson about family and the pleasure and heartbreak that comes with it.