On 19 April 1940 Celso Costantini prophetically wrote in his diary that if Italy followed Hitler into war, it would be allying itself with the “Anti-Christ.” Within weeks, Mussolini’s fascist regime plunged Italy into the destructive maelstrom of global military conflict. The ensuing years brought world war, the fall of fascism, occupation, liberation, and the emergence of a new political order. The Secrets of a Vatican Cardinal is an extraordinary and detailed behind-the-scenes account of crucial episodes in Europe’s wartime history from a unique vantage point: the Vatican and the Eternal City. Costantini, a close advisor to Pope Pius XII, possessed a perspective few of his contemporaries could match. His diaries offer new insights into the great issues of the time – the Nazi occupation, the fall of Mussolini, the tumultuous end of the Italian monarchy, the birth of republican democracy in Italy, and the emergence of a new international order – while also recounting heartbreaking stories of the suffering, perseverance, and heroism of ordinary people. Less than a century later, with the world’s attention gripped by the first papal resignation in six hundred years, The Secrets of a Vatican Cardinal presents a clear-eyed, fascinating, and complex portrait of the Roman Catholic Church’s recent history.