It will come as no surprise to the gifted Auster's ( Moon Palace ; The Music of Chance ) many fans that walking on air, the implausible premise of his marvelously whimsical seventh novel, is treated with convincing gravity. Walt Rawley recounts his life: an orphan born in 1924 with "the gift," he was seized by his master, Mr. Yehudi, a Hungarian Jew who taught him to levitate. Yehudi takes the boy from St. Louis to his own Kansas menage, which consists of Mother Sioux and Aesop, a young black genius. (Also influencing Walt's life is classy, henna-headed Marion Witherspoon, a seductive mom figure from Wichita.) After harsh training, Walt tours with his mentor as "the Wonder Boy," aka Mr. Vertigo. Crammed into this road saga is the potent Americana of myth: the 1920s carnival circuit, Lindbergh's solo, the motorcar, the ethnic mix, the Ku Klux Klan and the Mob, baseball and Kansas, "land of Oz." Diverse mishaps descend, but eventually Walt glides into old age and writing. The characters speak a lusty lingo peppered with vintage slang, while a postmodern authorial irony tugs their innocence askew. The prose grows particularly electric when demystifying "loft and locomotion." Implicit is an analogy between levitation and the construct of fiction: both require fierce discipline to maintain a fleeting illusion.