"Christopher seems supremely ill equipped to be a narrator," Haddon agrees. And yet, as he discovered early on, Christopher's apparent disabilities were actually a safeguard against the literary traps that ensnare so many novelists. "He never explains anything too much, he never tries to make the reader's mind up one way or the other," Haddon says. "He just paints a picture and leaves you to decide. He is very good at show, don't tell."