Margot is the survivor of a devastating accident in which her entire family drowns in their car. She is taken in by the family of a lawyer, a former colleague of her dad's who owes her father his life. They live on an enormous, isolated family estate. She is asked to be a companion to their daughter, Agatha, a vivacious 16-year-old girl who has inexplicably become catatonic. Laura, Agatha's mother has very strict codes of behavior in general and in how Margot relates to Agatha. The house is remote and completely cut off from the outside world, no cell service, no wi-fi and a long way from the nearest town. Margot starts to sense that things are not as they seem. The author is very skillful in creating an unsettling, foreboding and claustrophobic atmosphere. The reader is on edge throughout. The Companion feels like classic gothic horror, although it is set in the present day. It's a perfect haunting, creepy thriller and I read it in two days.