Claire and Matt are no longer together, but decide what's best for their daughter Scarlett is to have a 'normal' family Christmas. They can't agree on who said they should bring their new partners, but it's too late to pull the plug. Claire brings her new boyfriend Patrick, a seemingly sensible eligible-from-a-distance Iron-Man-in-Waiting. Matt brings Alex - funny, smart, and extremely patient. Scarlett brings her imaginary friend Posey. He's a rabbit. The grown-ups grit their teeth over Forced Fun activities, drinking a little too much after bed-time, and oversharing classified secrets about their pasts; and before you know it, their holiday is a powder keg that ends where this story starts: with a frightened, tearful call to the police. But what happened? They said they'd all be ADULTS about this...