Sixty years after Dorothy L. Sayers began her unfinished Lord Peter Wimsey novel, "Thrones Dominations," Booker Prize finalist Jill Paton Walsh took on the challenge of completing the manuscript---with extraordinary success. "The transition is seamless," said the "San Francisco Chronicle"; "you cannot tell where Sayers leaves off and Walsh begins." "Will Paton Walsh do it again?" wondered Ruth Rendell in London's "Sunday Times." "We must hope so."...