The Last Confession, Festival Theatre, Chichester

The stage of the Chichester Festival Theatre is awash at the moment with elderly men in bright red frocks bitching away. The Vatican, and its snake pit of Cardinals, is the setting for Roger Crane's absorbing conspiracy thriller exploring the dubious circumstances of the death of John Paul I.

He was known as "the smiling Pope", but just 33 days into his reign he was found dead in bed, clutching not The Imitation of Christ, as the Vatican spin doctors initially claimed, but papers relating to Mafia-tainted banking scandals. Can it be mere coincidence that his end came just as he was getting rid of the reactionary heavies in the Curia who opposed his liberal outlook on artificial birth control and on revolutionary priests in South America?

The play's central character is not, however, the Pope but a Pope-maker - Cardinal Giovanni Benelli. In Crane's version of events, Benelli is the wheeler-dealer who swung the election in favour of the unlikely Albino Luciani, and then after Luciani's demise the Polish outsider, Karol Wojtyla. Unfolding in an extended flashback, the drama takes the form of Benelli's dying confession, in which he accuses himself of failing to give John Paul I the support to fight off the sharks in the Curia and of agreeing to curtail the investigation when tempted with the prospect of his own pontificate.

Premiered in an assured and stylish production by David Jones, the play grips the attention throughout and is admirably free from the tunnel-vision derangement that usually besets conspiracy theories. But some of the grander-sounding questions it asks - for example, "Where is the line between divine providence and human intervention?" - prove to be well beyond the scope of this writer, a New York lawyer here making his debut as a dramatist. The dialogue has more than its fair share of ping-pong melodramatics, as exemplified at the end of Act I when his confessor asks if Benelli fears death "because you have lost God". "No," replies the Cardinal, and you half expect the audience to join in with the clunky, inevitable continuation, "because I might find him."

Neither Crane nor his characters possess the knack of making casual conversation. There's a dismally lifeless scene where John Paul I (beautifully portrayed by Richard O'Callaghan as a sweet-natured but increasingly tough individual) chews the fat with a Vatican gardener about the paradox of a Pope living in a palace and needing guards. The lines are relentlessly pointed ("This is the House of God, not the House of Rothschild") and over-starched with significance ("Be careful of power - your punishment may be finding it.")

And yet, and yet. The play does intriguingly explore whether wielding temporal power and performing Christ's ministry are reconcilable, as well as the mentality of the reactionaries for whom preserving the institution overrides all other moral considerations.

William Dudley's splendid design - with Renaissance doors clamped onto mobile, cage-like walls - presents the Vatican as a sumptuous prison, a place of stifling institutional restrictions where "everything is confidential and nothing is secret".

One of the chief pleasures of the show is the excellent group work of a host of senior actors. Charles Kay is on lethally waspish form as the high-handed Cardinal Felici and Bernard Lloyd wonderfully stubborn and intimidating as Villot. Above all, the play is to be congratulated for having lured back to the stage the superlative David Suchet, who invests the self-doubting, politically canny Cardinal Benelli with depth and complexity.

To 19 May (01243 781312)