Born into a simple family on the northern edge of Italy, Angelo Giuseppe Roncalli spent much of his working life in unfashionable diplomatic postings in Sofia and Istanbul until his surprise appointment as Papal Representative in Paris in the difficult years immediately after World War II. In 1953, he became Patriarch of Venice in what was assumed to be the last appointment of a man whom many considered worthy but naive. When at the age of 77 he was elected to succeed the austere and aristocratic Pope Pius XII, they called him the stop-gap Pope, not expected to reign long or to do much. Yet, in a mere four-and-a-half years, Pope John XXIII transformed the Roman Catholic Church. He called the Second Vatican Council and gave it a vision for the future. He mediated in the Cuban missile crisis and promoted dialogue between Kennedy and Khrushchev. With his encyclical, "Pacem in Terris", he made hope seem possible again. This biography is by the author of "The Year of Three Popes" and "Paul VI - The First Modern Pope".