Breaking a promise can have deadly consequences.

Grandma Maureen escapes the nursing home and walks into the water. The McNamara curse strikes again as another member is taken by the sea.

Shaelyn, Cordelia, and Riley—triplet terrors who once dreamed of stardom and true love—return home to mourn the woman who raised them. Shaelyn lost the man of her dreams and had to raise their children alone while running the family business. Cordelia married her childhood sweetheart and became his princess, but he began punishing her after she failed to meet his expectations. Riley's a famous musician, but a life of excess and regret has taken its toll.

Someone else lurks in Provincetown, eager for the sisters' reunion—a mysterious man who's watched them from afar for years. One of the sisters has a secret, a bargain struck which must be fulfilled or else disaster will follow. The McNamara Girls have no choice but to set aside their differences and unite against a predator whose vengeful obsession refuses to be denied.