After the unexpected demise of the unnamed pope due to a heart attack, the College of Cardinals convenes in a secretive papal conclave to elect the new leader of the Catholic Church, under the guidance of Cardinal-Dean Thomas Lawrence. To his astonishment, Archbishop Benitez of Kabul appears, revealing that he was clandestinely appointed as a cardinal by the late pope.
As the conclave unfolds, four primary candidates emerge for the papacy: 1) Bellini, who embodies the progressive ideals of his predecessor, 2) Adeyemi, a socio-economically forward-thinking individual with conservative moral standings, 3) Tremblay, representing mainstream conservatism, and 4) Tedesco, a traditionalist advocating for the church to retreat from the Second Vatican Council’s inclusive policies. Tedesco's bigotry and abusive demeanor toward his staff paint him in a negative light, while speculation arises that both Tremblay and Adeyemi may have exploited their influence in the Vatican, contributing to the late pope's demise.
As the key players in the Church's liberal narrative, Bellini and Lawrence emerge as prime contenders for the papacy. However, both express their reluctance to accept the role for varied reasons. Bellini, while intrigued by the position, believes that a façade of disinterest will garner him respect from his peers. In contrast, Lawrence grapples with a profound crisis of faith that previously led him to contemplate resigning from his post. Despite initially voting for Bellini, Lawrence seems to hold back complete support, creating a tension that does not go unnoticed.
Prior to the first voting round, Lawrence delivers an impassioned speech urging the cardinals to advocate for diversity—a moment many interpret as a veiled campaign address. Intriguingly, Lawrence begins to gather research against rival candidates, justifying it as necessary due diligence for the defense of the Church, despite the breach of conclave protocols. A confidant of the late pope informs him that Tremblay had been dismissed on the day of the pope's death, a claim denied by Tremblay who produces an eyewitness to discredit the allegation.
As voting commences, no candidate secures the requisite two-thirds majority. Adeyemi emerges with a slight advantage while a handful of votes go to Lawrence, igniting Bellini's ire. Confronted with a lack of a unified liberal candidate, the progressives rally behind Adeyemi. In an unexpected twist, Bellini—a vocal opponent of Adeyemi's homophobia—strikes a deal to back Tremblay in exchange for a coveted bureaucratic position.
The tension escalates as one of the nuns entrusted with catering during the conclave boldly confronts Adeyemi in the cardinals' cafeteria, revealing to Lawrence her secret past with him: she bore Adeyemi's child at a young age. When confronted, Adeyemi admits to this truth and pleads for her forgiveness, but the atmosphere shifts as a whisper campaign undermines his candidacy, illustrating the cutthroat nature of the conclave.
Unbeknownst to many, Adeyemi suspects a conspiracy after learning that the nun was recently moved from Africa to the Vatican—an assignment he believes was orchestrated by Tremblay. In a desperate attempt to thwart Tremblay, Lawrence attempts to use the threat of exposure for personal gain, but Tremblay counters Lawrence's manipulations, revealing his own agenda.
In a pivotal scene, Lawrence uncovers incriminating documents in the late pope's residence that expose Tremblay's corrupt activities regarding vote buying. Faced with a moral dilemma, Bellini advocates for the destruction of the evidence but chooses to stand by Lawrence instead, shifting his allegiance toward solidifying a path to rid the conclave of Tremblay's grasp.
As the conclave progresses, a horrific suicide bombing in Rome results in mass casualties, shaking the very foundation of the Church's deliberations. Tedesco's reactionary rhetoric inflames tensions, demanding conflict against perceived threats, while Benitez, an advocate of reconciliation, challenges the Church to embrace evolution rather than perpetuate outdated traditions.
Ultimately, a heartfelt amalgamation of conviction among the cardinals leads to the election of Benitez as pope, yet not without its complications. Shortly before the announcement, Lawrence is faced with a shocking revelation about Benitez's past, potentially shattering his newfound papacy. Confronting Benitez, Lawrence learns of his intersex identity and the delicate choice he made regarding his anatomy, ultimately leading Lawrence to prioritize loyalty over ambition by keeping Benitez’s secret.
As the jubilant crowds celebrate the election of their new pope, Lawrence gazes out from his dormitory window, entangled in a web of politics, faith, and sacrifice, reflecting on the profound implications of power and the cost of ambition.
