When Sarah was seventeen years old, she hid in a wardrobe while her mother was murdered in the bedroom.


As the weeks and months passed, Sarah gradually moved on from the horror of that night and managed to settle into her changed family life.


After the police confirm that her mother was one of three similar victims the case goes cold. Until Sarah receives a letter: "I didn't know you were there, or I would never have done that. Sincerely, Yours."


And, so begins a terrifying game of cat and mouse as the killer collects more victims and continues to elude police, all the while, sending Sarah letters.


As the killer gets closer, Sarah wonders if she comes face to face with him, will she opt for mercy or murder?