"Unbreakable," like most of M. Night Shyamalan's films, reveals itself slowly. The film is downbeat, depressive, and is presented as a mystery. David Dunn (Bruce Willis) is the only survivor or a massively destructive train accident, and he doesn't have a scratch on his body. Although he evaded death, David is too despondent over his flagging marriage to much notice how extraordinary it is. Once a football hero in high school, David now works as a mere security guard, resigned to a dull...