"I'm on my way back. I was one of the first they took away." So begins Robert Kelly's remarkable science fiction novel about a literally divided self. "I" is Billy, the book's protagonist, a boy who is captured by a group of aliens who take him to a cave and meticulously, if seemingly by caprice, remove his "young pure smokeless lungs" and other internal organs to replace them with two gray squirrels, a live hawk, a shoe, and a variety of other bizarre objects. Billy's body and mind are spun off into a curious twin, one whose adventures Billy is forced by his captors to watch and try to make sense of-not a simple task when he sees his doppelg nger stealing everything from him- body, name, family, his beloved Eileen. Complicating matters, and forcing Billy deeper into his ironic journey of self, is a mysterious pamphlet called "The Book from the Sky," written by what may be yet another variation of Billy himself, Brother William. This stunningly imaginative work, echoing the late novels of Iris Murdoch and the fantasies of Robert Charles Wilson and Jonathan Stroud while remaining inimitably Kelly's own, offers adventurous readers a "cabinet of wonders" not unlike the body of his beleaguered young hero.