The Vatican within Rome is the spiritual centre of global Catholicism. It is also the smallest recognised and independent city state in the world. In terms of its influence and wealth, it is remarkably powerful, and thus a choice subject for Roger Crane’s play The Last Confession.

It is no surprise that the play, directed by Jonathan Church, brings together issues of faith, doubt, power and greed at the critical period of the papacy that included the brief office of Pope John Paul (played by a very engaging Richard O’Callaghan).

Was he the right person to become pope? Was he murdered after a mere 33 days for trying to make too many changes, or perhaps crucially threatening ones? The ingredients for a murder mystery are all there.

David Suchet (yes, Hercule Poirot, and much more) is compelling as the central figure, Cardinal Benelli. Rather against his wishes, he has become the king-maker – or rather, pope-maker – and yet he also feels the pull towards power for his own sake.

Doubt is his constant companion, along with bouts of self-judgement. There is much about the church that he feels is wrong, including murky financial dealings. The death of John Paul comes just as some of the characters intimately involved with that state of affairs are about to be brought to account.

Fotini Dimou’s costumes are splendid. William Dudley’s set is a beautiful work comprising high railings and wooden doors adorned with pediments. It is frequently moved about in different configurations that are effective, though the act of repositioning them is occasionally intrusive. Perhaps the cage metaphor indicated by the railings does too blatantly suggest how lives can become trapped in particular practices and definitions.

The production features a sterling cast. Beyond the captivating Suchet and O’Callaghan already mentioned, I would cite Philip Craig (whose character is deliberately unclear at first), Nigel Bennett as Cardinal Villot, and Kevin Colson as Cardinal Baggio.

Suchet’s Benelli pursues the chance of an official investigation of John Paul’s demise in a climactic series of confrontations that reveal an ugliness capable of destroying a man’s sense of his own worth.  At one point a character says: “Churches are not run by saints. They are run by men who understand power.”

Benelli must decide what power means, and what place faith has in his life.

The Last Confession is playing at Her Majesty’s Theatre until Saturday, August 30.