The hypocrisy of the Roman Catholic Church is the underlying theme of Death of a Pope. Failure in its mission to promote the spiritual growth of the faithful comes to light in this, the information age, where secret agendas no longer remain secret.
Pope Boniface, Raffaele Vincenzo Valentini, the last true Vicar of Christ is in jeopardy of being swept aside by the political corruption of the Holy See. He is visited by the mystical Father Frederick Monahan, who died on the RMS Titanic in 1912 and remained behind on this plane to give spiritual assistance where required. Aware of the plot against Raffaele, Father Freddie consuls and warns him of impending trouble.
Father Freddie's mission is to influence, but never to interfere with the destiny of anyone. Realizing Raffaele may succumb to the intrigue of the Holy Sea, he visits Father Marc, a selfless young American priest and begins to groom him for the possible soon to be vacated throne of the Catholic Church.
When Raffaele is murdered, the wheels for the election of the new Pope are put into motion, bringing together the characters who are to participate in the unfolding drama. Father Freddie makes a surprise appearance during the first day of the conclave. In addition to berating the participants of their hypocrisy, he indicates that the individual responsible for the murder of Pope Boniface is among them. As he vanishes in a blinding light, the doors of the Sistine Chapel are unlocked, sending the participants fleeing.
Father Marc is drawn into the conclusion of this tale by the gift Father Freddie gave him during their first meeting, resulting in his election as the next Supreme Pontiff, the Bishop of Rome.