Roy Orbison was a self-conscious young man who transmuted anxiety into gold. As recording artist, author and Milwaukee expatriate John Kruth reports in his biography of the singer-songwriter behind “Only the Lonely,” “Pretty Woman” and “Running Scared,” even Orbison’s guitar was one of the masks concealing his doubts—along with his trademark dark shades. Kruth is an amusing, at times hilariously funny writer, but the sometimes snarky humor doesn’t conceal his sympathy for Orbison or eclipse his exhaustive research. Kruth talked to just about everyone still alive who knew Orbison, the greatest introvert ever to achieve rock stardom.