Audrey St. Vrain has grown up in the shadow of someone who doesn't actually exist. Before she was born, her mother, Camilla St. Vrain, wrote the bestselling book Letters to My Someday Daughter, a guide to self-love that advises treating yourself like you would your own hypothetical future daughter. The book made Audrey's mother a household name, and she built an empire around it.

While the world considers Audrey lucky to have Camilla for a mother, the truth is that Audrey knows a different side of being the someday daughter. Shipped off to boarding school when she was eleven, she feels more like a promotional tool than a member of Camilla's family. Audrey is determined to create her own identity aside from being Camilla's daughter, and she's looking forward to a prestigious summer premed program with her boyfriend before heading to college and finally breaking free from her mother's world.

But when Camilla asks Audrey to go on tour with her to promote the book's anniversary, Audrey can't help but think that this is the last, best chance to figure out how they fit into each other's lives—not as the someday daughter and someday mother but as themselves, just as they are. What Audrey doesn't know is that spending the summer with Camilla and her tour staff—including the disarmingly honest, distressingly cute video intern, Silas—will upset everything she's so carefully planned for her life.