4 stars

It's an irresistible pleasure watching veteran actors Anthony Hopkins and Jonathan Pryce together on screen as Pope Benedict and his successor, the head of the Catholic Church today, Pope Francis.

Each Welshmen has a commanding presence and they are each thoroughly believable as good men of God.

In the hands of another director, this drama about the struggle between Benedict and Francis, between the conservative and the liberal forces they represented in the church, could have been dull and unenticing. In the hands of Brazilian director Fernando Meirelles, it is anything but.

Screenwriter Anthony McCarten, who has had his fair share of success recently with Darkest Hour and Bohemian Rhapsody, has done lively and engaging work here. It is not known what Benedict and Francis actually said to each other during the three conversations they had in 2013, but McCarten has some engaging views on it.

Music direction is lively too. In an early scene set in 2005, when Cardinal Bergoglio (later Pope Francis) bumps into Cardinal Ratzinger (later Pope Benedict) in the washroom, he is humming a pop tune. The same tune, ABBA's Dancing Queen, is the soundtrack when cardinals from around the world assemble to elect their next pope. Playful brio in this Meirelles film, from the variety of camera angles and positions to the soundtrack, is everywhere.

Back in 2005, after the death of Pope John Paul II, the church was looking at its options in challenging times. Would it continue with the process of liberalisation that the late pope had overseen, or to revert to a more stringent traditionalist approach? It chose to install the conservative bishop from Germany, Joseph Ratzinger, as its new leader and reaffirm the church's fundamental doctrine. Benedict XVI brought more Latin back in again, and the traditional red papal shoes reappeared on his feet.

The Church's new conservatism under Benedict caused Bergoglio, the archbishop of Buenos Aires, to fly to Rome to offer his resignation. The popular, liberal cardinal hadn't even reached retirement age. What Bergoglio didn't know was that his pope, who was older than most popes had ever been to hold office, was planning to step down. He wanted to persuade Bergoglio, his strongest critic, to succeed him. The pope was taking the almost unprecedented decision in 2013 to resign from the papacy.

As to be expected, the worldly archbishop from Argentina and the former academic from Bavaria are worlds apart. Benedict reveals another side as the pianist who enjoys playing his favourites, including Berlin cabaret music. Bergoglio loves soccer and dancing the tango.

The film delves into Bergoglio's past when as a young man just about to marry he makes a U-turn into the confessional box and joins the Jesuits. Another flashback shows his shameful actions under the Argentinian junta.

Yet, despite some conversation about child abuse in the church between Benedict and his cardinal, this moment is far too brief. It's a missed opportunity.

The Two Popes is still a rich and entertaining experience. It's a terrific extended conversation despite wasted opportunities, bringing an engaging, humanistic perspective to the issues the church faces in the modern world.