Millie cleans the beautiful Winchester house every day. He picks up their daughter from school. He cooks a delicious meal for the whole family before heading upstairs to eat alone in my little attic room.

He tries to ignore how Nina makes a mess only to watch as the housemaid has to clean it up. How he tells strange lies about his own daughter. And that her husband, Andrew, seems more and more devastated by the day. 

Nina's life is perfect. Wardrobe, fancy car, perfect husband. Only once does Millie do something to experience what it's like to live like her employer. But she soon finds out about it. And the door to the attic room only locks from the outside...
 
A trapped Millie reassures herself: The Winchesters don't know who she really is.
They don't know what she's capable of...

The above description comes from the publisher.