“Nelson nods again. ‘It’s every parent’s worst nightmare. The worst, the very worst. When you have children, suddenly the world seems such a terrifying place. Every stick and stone, every car, every animal, Christ, every person, is suddenly a terrible threat. You realise you’d do anything, anything, to keep them safe: steal, lie, kill, you name it. But sometimes there just isn’t anything you can do. And that’s the hardest thing.”