I would never have dreamed that the death of an obscure 20th-century Pope could provide inspiration for a beguiling theatrical whodunnit or at least a "did-anyone-do-it?" The Last Confession, premiered and much admired at Chichester's Festival Theatre in May, reveals the limitations of my dreams.

Its author, New York lawyer Roger Crane, regards the death of John Paul I, who died in 1978 of an apparent heart attack 33 days after his installation, as the murderous finale in a Vatican conspiracy drama and the sign of fierce ideological conflict between this radical Pope and reactionary cardinals.

The Last Confession does not merely delve into skulduggery. Crane, whose dialogue often sounds as if sententiously minted by some Hollywood scriptwriter familiar with religious epics, offers no information about what published sources he relied on to level his sensational charges. He does, however, suggest that John Paul's greatest supporter, the self-centred Cardinal Benelli, was prone to such nagging ambition to become Pope that he persuaded himself to be politic and abandon demands for an inquiry into John Paul's death.

The play takes the distinctly tired form of the flashback, from the moribund moment when David Suchet's charismatic, brooding Benelli decides to make a final confession. The last five years of his life begin to be replayed before us.

William Dudley's grand, impressionistic design conceives the Vatican as an imposing prison, with grille-like walls and marble-framed doors, set against a photographic back-projection of St Peter's. David Jones's evocative production hustles smoothly through the dusky corridors of power and reeks of suave menace as cardinals prowl and cluster in false shows of deference.

The laboriously over-extended first half shows the closing phase of Paul VI's undecisive papacy in rickety decline and fall. Something is most amiss. Why does Stuart Milligan's big bruiser of an American, Bishop Marcinkus, plan to sell the Catholic bank of Venice? Will Bernard Lloyd's blustering, conservative Cardinal Villot succeed in getting the liberal Benelli dispatched from the Vatican to distant Zambia or Paraguay? Instead, though, Benelli becomes the influential power-broker who plays the decisive role in securing the election of Richard O'Callaghan's timid, child-like John Paul I.

Having attempted one day to rid himself of cardinals obstructive of reform, the Pope dies the same night. Crane turns to thriller-formatting, with Benelli taking the unofficial role of investigator and chief accuser.

Suchet's impressive Cardinal, a rueful figure who cannot come to terms with his longing for worldly glory at the expense of religious faith, unpacks his heart to Michael Jayston's authoritative, mysterious confessor.

In closing moments of grim irony he burns his confession, as if to obliterate his imperious ego.

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