Willis plays a Philadelphia security guard whose marriage is on the verge of failing when he becomes the sole, unscathed survivor of a devastating train wreck. When prompted by a mysterious, brittle-boned connoisseur of comic books (Samuel L. Jackson), he realizes that he's been free of illness and injury his entire life, lending credence to Jackson's theory that superheroes--and villains--exist in reality, and that Willis himself possesses extraordinary powers. Shyamalan presents these revelations with matter-of-fact gravity, and he draws performances (including those of Robin Wright Penn and Spencer Treat Clark, as Willis's wife and son) that are uniformly superb. The film's climactic revelation may strike some as ultimately silly and trivial, but if you're on Shyamalan's wavelength, the entire film will assume a greater degree of success and achievement.