This is the amazing story of Sister Pascalina Lehnert (1894–1983), who was the personal confidant and secretary to Pope Pius XII for forty years, when he was the papal nuncio in Germany, and then for his whole pontificate. The Pope had great confidence in her wisdom, energy, and loyalty, and she became known as “the most powerful woman in the history of the Vatican.”

In 1918, the young nun Pascalina was sent to Munich to be the housekeeper of the new papal nuncio, Eugenio Pacelli. Though they seemed to have little in common, Pacelli became impressed by Pascalina’s directness, zeal, and alertness. During his delicate negotiations on the Concordat with Bavaria and Prussia, he benefited from Pascalina’s pertinent comments and clear-headed views. He was sad to leave her behind when he was appointed Cardinal Secretary of State in 1929 and moved to Vatican City—where women were forbidden to live. But Pascalina's loyalty and strong support were missed, and she was invited to work in the Vatican—the first woman ever to do so.

As part of Pacelli's Vatican household, she contended with the intrigues and rivalries of men who resented the privileges she enjoyed and the power she wielded. But all the in-fighting soon paled before the horrors of the war, which began the same year that Pacelli was elected Pope and became Pius XII. As the war tore Europe apart, the pope put his life, and the papacy itself, on the line by opposing the Nazis and Fascists. 

Visiting the injured and steering through plots and conspiracies, Pope Pius XII relied heavily on Sister Pascalina, his link to the world of the suffering and the persecuted. Thanks to the fearlessness of Rome’s clergy and the tirelessness of Pascalina, he managed to save the lives of many Roman Jews. As head of the private papal charity, Pascalina used her organizational skills to help thousands. She remained at Pacelli’s side until his death in 1958, as his important confidante, valued adviser, and friend—God’s mighty servant to the end.