I love my eight-year-old son Riley more than anything. Yet the truth is, I fear for him. It's hard being a single mother. It's even harder when you can't let anyone come close. When you avoid parents at the school gate, scared you'll give too much away. Riley thinks his father died in a car crash. He has no idea what really happened eight years ago - why I ended up sobbing in the dark on the kitchen floor. Every mother is protective of her child. But not every mother is constantly glancing over her shoulder. Everyone has secrets. But not everyone is terrified of their lies being exposed, their lives unravelling when it all comes out. So when Riley disappears from our garden on a cold winter's afternoon, I know that he hasn't just run away. I'd do anything to save my son - but if I tell the truth, I might lose him for ever.