Unforgettable. The author lets the story tell itself. There are acts of heroism as well as human failing (trapped people hear contradictory messages about evacuating or waiting for rescue; a tired office worker with bad feet refuses to continue downstairs, unwittingly saving herself and her rescuers, who are spared in a miraculous safe spot as the North Tower falls). The illustrations are heartbreaking. Children will be able to see their own parents in the figures of men and women trudging down staircases, prying an elevator door open, stumbling through smoky offices.