Dan Garvie can't move on from a thing he didn't do. He saw the boy. He knew he needed help. But he ran and hid and a terrifying serial killer got away. Years later, Dan is a successful criminal psychiatrist, unpicking the very darkest of human behaviour. Because, despite what he saw that day, Dan knows there's no such thing as a monster. But now his father, John, has disappeared. And days before he vanished, he'd found a body near his home, which might just link back to the serial killer from that fateful day. Is this a chance for Dan to save his dad and find redemption or is he walking straight into a trap?