Shortly after Christmas, a message arrives at Sophie's house, scrawled across her own round robin newsletter: “He's going to leave you. Let's see how smug you are then, you stupid bitch.” Perhaps she should ignore it, but she ignored the last one. And the one before that. Now it's time to take action. But when a simple plan to identify and confront the other woman goes drastically and violently wrong, Sophie must go to extreme lengths to keep her life and her family together - while never letting on about her devastating secret.