Their Little SecretShe says she's an ordinary mother. He knows a liar when he sees one. Sarah thinks of herself as a normal single mum. It's what she wants others to think of her. But the truth is, she needs something new, something thrilling. Meanwhile, DI Tom Thorne is investigating a woman's suicide, convinced she was driven to do it by a man who preys on vulnerable women. A man who is about to change Sarah's life.