Newly elected Pope Pius XIII (Jude Law), a.k.a. Lenny Belardo, defies expectations as he settles in at the Vatican to begin his reign. The youngest and first American pope in history, Lenny's ascension was orchestrated by the Vatican Secretary of State, Cardinal Voiello (Silvio Orlando), who mistakenly believed the young pope would follow his lead on policy and protocol. Instead, Lenny shuns Voiello and tasks his confessor, Don Tommaso (Marcello Romolo), to share details on the private thoughts and motives of those in his inner circle.
Meanwhile, as Cardinal Spencer (James Cromwell), Lenny's onetime mentor, stews about being passed over as pontiff, the new pope flies in Sister Mary (Diane Keaton), who raised him since he was delivered to an orphanage at seven, to serve as his chief advisor. While Sister Mary urges Lenny to put aside dark memories and focus on leading his billion followers, the young pope shows no inclination towards making himself available, either to the College of Cardinals or to the masses.
