Donnabella Sun doesn't have it easy. Her stepfamily forces her to work around the house constantly. When she is offered the choice to spend the summer with them at the beach, she accepts it, but her twin step-siblings will do everything in their power to ruin her stay. After downloading a messaging app on her phone, Donnabella quickly makes a new anonymous online friend.

Donnabella's next door neighbor and best friend, Colin Booker, also travels to the beach with his family for the summer. Being the beach heartthrob makes his summer a maze of girls. Colin wants to spend every moment with his best friend, but Donnabella is too busy with her job and family.

Every July Fourth, the Booker family hosts a masquerade party on the beach, and the whole town attends. Donnabella has a chance to meet her online friend, but her stepfather forbids her to go. However, she starts plotting to go against his wishes. As Colin and Donnabella become closer, Donnabella's relationship with her online friend grows stronger. The summer becomes a delicate dance of telling lies and keeping secrets—even to and from best friends.