Mr. Bones, the canine hero of Paul Auster’s astonishing new book, is the sidekick and confidant of Willy G. Christmas, a brilliant and troubled homeless man from Brooklyn. As Willy’s body slowly expires, he sets off with Mr. Bones for Baltimore in search of his high school English teacher and a new home for his companion. Mr. Bones is our witness during their journey, and out of his thoughts, Paul Auster has spun one of the richest, most compelling tales in American...