When the Pope unexpectedly dies of a heart attack, Cardinal Thomas Lorenz (actor Ralph Fiennes) learns that in his final decree, the Holy Father has appointed him to lead the conclave - a sacred, centuries-old and one of humanity's most mysterious rituals designed to elect a new pope.
There are four front-runners in the race for the new Pope, all with their own secrets, secret weapons, and a surprisingly worldly will to win. As Lorenzo watches the escalating battle unfold, he realizes he has suddenly found himself at the center of a conspiracy that could shake the very foundations of the Catholic Church.