Cass is having a hard time since the night she saw the car in the woods and the woman who was killed. Since then she's been forgetting everything: where she left the car, if she took her pills, the alarm code, why she ordered a pram when she doesn't have a baby....
What she can't forget is the woman she might have saved, the terrible nagging guilt, the silent calls she's receiving and the feeling that someone's watching her.