PARIS— WHAT did Pope Pius XII know about the Holocaust? The question is not new. Since the mid-1990's, when the Vatican began considering the wartime pontiff's beatification, a flurry of books have charged that he ignored strong evidence of the continuing extermination of Jews for fear of German reprisals. Now, with ''Amen,'' the latest in a long line of powerful political movies by the Greek-born director Constantin Costa-Gavras, the case against Pius XII has been brought to the screen.

Mr. Costa-Gavras's approach, though, is not that of a prosecutor. Rather, as in ''Z,'' ''The Confession,'' ''Missing'' and other films in a career dating to 1965, he has turned a critical political moment into a human drama with the pace of a thriller. And more than ever he raises issues of conscience. By arguing that individual courage in the face of oppression and barbarity is a moral imperative, he implicitly asks: how would we act in the same situation?

''For me, the idea of silence is the film's main theme,'' Mr. Costa-Gavras, 69, said in an interview at his home in Paris, where he has lived for the last four decades. ''The silence of the people, the silence of a lot of people in the church. Some people dared speak out, but the leaders of the church stayed silent. So it is also a metaphor for all the silence.''

The movie, which opens in New York and Los Angeles on Friday, is adapted, in English, from Rolf Hochhuth's play ''The Deputy,'' which Mr. Costa-Gavras saw in Paris in 1964. The play, which caused a scandal in its day, dwells on Pius's refusal to denounce the mass murder of Jews, but Mr. Costa-Gavras has refocused the plot on an unlikely pair of resistants -- a Nazi and a priest -- who come to personify the tragedy of the papal silence.

Driving the narrative is the true story of Kurt Gerstein, an SS officer and Protestant who struggled to inform the Vatican of the extermination of the Jews at the same time he was delivering Zyklon B, the poison used in the gas chambers. In July 1945, after writing a long report about the death camps, he committed suicide. With Mr. Hochhuth's play, his wartime role finally became known. Today, for some German Protestants, he is a martyr.

The movie stays close to the known facts about Gerstein, who is played by the German actor Ulrich Tukur: his stunned reaction to the discovery of the gas chambers, his immediate disclosure of the death camps to a Swedish diplomat, his efforts to sabotage his deliveries of Zyklon B, his failure to convince Protestant pastors to speak out and his attempt to inform the Papal Nuncio in Berlin about the escalating genocide.

Poetic license takes over in the creation of Riccardo Fontana, an Italian Jesuit who is serving as the Papal Nuncio's secretary. Played by the French actor and director Mathieu Kassovitz, Father Riccardo is so persuaded by Gerstein's testimony that he assumes responsibility for informing Pius XII of the organized murder of Jews.

''The priest is a composite of at least four priests,'' Mr. Costa-Gavras explained. ''One was an Italian army chaplain who returned from the Russian front through Poland and Czechoslovakia and saw these things happening and went directly to the pope. And the pope apparently said what we say in the movie: 'I cannot do anything for them. I pray for them.' But for me, the pope is a secondary character. The main characters are Gerstein and the priest.''

Indeed, by risking their lives to uphold Christian values, they serve as counterweights to the remote figure of Pius XII (Marcel Iures), who is surrounded by fawning prelates until the moment that Father Riccardo breaks through the protective ring to denounce the extermination of Europe's Jews. Yet even when Rome's Jews are rounded up barely two miles from the Vatican, the pope acts only to save Jewish converts to Christianity.

Mr. Costa-Gavras, who was baptized into the Greek Orthodox Church but now describes himself as a nonbeliever, insists that his purpose is not to attack the Roman Catholic Church as such, but rather to look at the misuse of the church's immense power. And in the absence of public access to the Vatican's still-secret wartime archives, he remains convinced by his reading and research that only moral failure can explain Pius XII's silence.

But having dealt with both right-wing and Communist repression in previous movies and even indirectly with Nazi death camps in ''Music Box'' (1989), he said that he still could not grasp how Europe, with 3,000 years of civilization, could have spawned the Holocaust. It was this question that led him to probe what he called ''the other side'' -- the German side -- of the genocide.

He and his co-writer, Jean-Claude Grumberg, therefore created another character crucial to the story: an SS doctor, played by the German actor Ulrich Mühe, who variously befriends, manipulates and threatens Gerstein. With his mixture of charm, intelligence, cruelty and cynicism, he symbolizes both the gross perversion of German civilization and the ignominious role played by many doctors in the death camps.