The McCanns have been through a terrible ordeal over the past two years, but they say nothing can be worse than the early days after Madeleine's disappearance. "I think almost everyone knows that feeling of terror if you're a parent and you've got a child in the supermarket and you momentarily lose them," Gerry says. "It's something that no parent should have to go through. ... It's just the most devastating, horrible sensation. Fear for your child and your whole existence.You family existence."