Camille Prescott has it all. A doting husband, two children, a charming home in a seaside enclave, and a beautiful, fixed smile that exudes normalcy. But behind her polished mask lurks a much different Camille--one with a padlocked vault of secrets. Raised by a vindictive and psychotic woman, Camille has gone to great lengths to bury her past and for good reason: if her mother ever finds her, she will kill her.

But nothing can prepare Camille for the day her six-year-old daughter, Georgie, starts showing signs of unsettlingly familiar behavior, including an imaginary new friend who casts a disturbing influence on everything the little girl says and does. Worse than that, Georgie's imaginary friend knows things about Camille's childhood, things Camille has never told a soul. Is it a coincidence or is Georgie's imaginary friend not so fictional after all?

As the family's stability cracks, so does Camille's facade, because the past isn't just coming for her and everyone she loves--it's already here.