even though roy and george had fully recovered , there were those unbearable few seconds where their fate was in flux , where all that was knowable was that two boys were probably on their way to death and there was nothing , not one single thing , that any adult watching could do about it , something that george only fully understood one afternoon when amanda , fifteen steps ahead of him on a pavement and still struggling with this whole new walking lark , had suddenly lurched sideways and fallen off a curb between two parked cars , momentarily disappearing from sight .