Fans of the Oscar-nominated movie “Conclave,” which is about a papal election, might think they have a head start on what’s to come next week. But

The secret vote that elected Pope Gregory X lasted from November 1268 to September 1271. It was the first example of a papal election by “compromise,” after a long struggle between supporters of two main geopolitical medieval factions — those faithful to the papacy and those supporting the Holy Roman Empire.

As viewers of the film will know, the papal conclave will take place entirely behind the closed doors of the Sistine Chapel, beneath its world-famous Michelangelo frescoes. Nobody outside the confines of the Vatican will know the outcome until the plume of white smoke will curl from its chimney,