Lenny Belardo is the youngest Pope in history but also the first American pontiff. His radical ideas could change the Roman Catholic Church, but underlying many of his choices is an ancient sorrow and a tormented relationship with his faith.

The Cardinal Secretary of State Voiello is worried about certain of the Pope’s initiatives which threaten to compromise the Vatican’s political relationships and the relationship with the faithful. Fears that are confirmed by the new Pontiff’s first, bewildering speech to the faithful in St. Peter’s Square.

Voiello decides to discredit the pontiff in order to create a scandal. In order to do so, he blackmails Ester into seducing the Holy Father, but the woman-while acting as if she's willing to engage in double-dealing, establishes ties of friendship with the pontiff and confesses her great sorrow to him: she is unable to have children. In the Vatican, meanwhile, word arrives of a shepherd from the provinces outside Rome, a certain Tonino Pettola, who claims to have seen the Madonna and who therefore asks to be officially recognized by the church. While out on a late-night stroll, Lenny sees Ester and her husband making love, and prays to the Virgin Mary to grant their wish and give them a child. In the meantime, the Pope has decided to appoint the fearful Vatican Master of Pontifical Liturgical Celebrations Gutierrez to investigate a child-abuse scandal involving an American high prelate, Cardinal Kurtwell, and announces yet another reactionary measure: he intends to expel all homosexuals from the Vatican.

Pius XIII indulges in a few hours of freedom outside of the Vatican walls in the company of his childhood friend Dussolier as he prepares to summon the cardinals to give them a message destined to revolutionize their concept of faith.

Ester gives birth to a boy. There is no doubt that the Pope is going through a period of weakness: but then the entire Vatican is weak, as it's paying the price of the crisis in consensus stirred by Lenny's reactionary policies. In the meantime, Dussolier-who has accepted the position of Prefect of the Congregation for the Clergy-has gone back to his diocese in Honduras to bid farewell to his community. But in Honduras, Dussolier has also been leading a double life, and he has some very dangerous relationships. Gutierrez, in the meanwhile, is elected cardinal and leaves for the United States, where he is being sent to investigate the Kurtwell case. Nine months into his papacy, Lenny gives an audience to the Italian Prime Minister, who is shocked both by the pontiff's anachronistic demands and by his incredible charisma. Lenny also decides to undertake a crusade against homosexual priests and asks Dussolier to take charge of it. The consequences are immediate and tragic.