It is just past ten o'clock on a cold Friday evening when Rebecca and her husband Jack's doorbell rings. Outside is a woman who introduces herself as Jack's ex-girlfriend Cara. And she's holding the hand of a shivering, blue-eyed, four-year-old girl. Who she claims is Jack's daughter. Rebecca is shocked to discover he has a child from his last relationship - even one he hadn't known about. Because becoming parents isn't part of their life plan. They like children, but they also love their freedom and spending time together uninterrupted; the way that, if they wanted to, they could travel the world at a moment's notice. But Cara needs them. Because Cara has a devastating secret that she can't tell anyone yet. Not even her daughter. A secret with the power to change all of their lives. A secret that will ultimately mean Rebecca has to ask herself - could she find it in herself to welcome her husband's child into her home, and into her heart?