"My finest, ferocious Caravaggio style"--that was his own phrase for his later manner; and that was the style I was aiming at, an interplay of light and shadow that would rivet the attention and, ultimately, draw the eye to darkness. At the beginning of Doris Langley Moore's deliriously entertaining final novel, bookseller and author Quentin Williams has just received the royalties (just over 4) from his two published biographies. In his...