In 1983 librarian Peter Stangl took his teenaged son and daughter to Budapest, to show them the city and the land where he had grown up. He wrote an account of that trip, which he titled "Pebbles," because a surprise encounter with some stones his mother had painted stirred up such strong memories of his boyhood. In time, Mr. Stangl expanded his memoir into a saga of memories of world-shaking events that he had witnessed as a boy and young man in...