Joanne knows how lucky she is—Richard is a wonderful husband, Evie is the most gorgeous baby girl, they live in a beautiful house—life couldn't be better. But then Richard's twenty-year-old daughter Chloe turns up. Chloe hasn’t spoken to her father since the day he married Joanne two years ago. But with the arrival of her baby sister Evie, Chloe wants to make peace. Richard is delighted, and since Joanne is struggling with the new baby, he suggests Chloe could move in and help.

It sounds like the perfect solution, even if Chloe doesn’t seem to like Joanne very much. But Joanne understands it’s not easy for her, and she's prepared to give her time. But then things happen that make Joanne feel like she’s losing her mind. She misplaces things, misses important appointments, gets dates wrong… Could Joanne be going mad, just like her own mother? Or is something more sinister happening? Is Chloe really here to help? Or has Joanne made a terrible mistake by letting her move in? And is it too late to ask her to leave?