Hinterland, NT Cottesloe, London

Sebastian Barry made his reputation with the excellent Steward of Christendom, about Thomas Dunne, a former chief superintendent of Dublin Metropolitan Police, wrestling with himself and with history in a home for the elderly. Barry's new play, in Max Stafford-Clark's brave Out of Joint production, appears to up the ante. Dunne was a father, and Steward certainly teased out all the affinities with Lear in his situation, but he was not the Father of the Nation.

Johnny Silvester (Patrick Malahide), the disgraced former Irish Taoiseach at the centre of Hinterland, in theory fits this double-edged bill. Under police protection in his Dublin mansion, he awaits the verdict of a tribunal on his nest-feathering corruption during his political heyday in the Seventies and Eighties. He is also awaiting a verdict on the state of his health. His family – his distressed, estranged wife (Dearbhla Molloy) to whom he was repeatedly unfaithful, and depressed suicidal son (Phelim Drew) – are not glowing testimony to his patriarchal gifts.

At Dublin's Abbey Theatre, the show caused a scandal as it was interpreted as a documentary drama about Charles Haughey. At the National, the the piece imparts a different shock. You boggle at how it fails to deliver on any front. It's a glorified promissory note; "fine writing" in desperate need of a stronger dramatic mechanism. I have no doubt that, in time, Stafford-Clark will be seen as the greatest, most influential director of new writing in post-Sixties English theatre, but not even his very imaginative varying of mood here can breathe life into Hinterland.

The questions it raises are potentially fascinating. To what extent can a modernising leader such as Silvester, act as if he were above the law in financial matters? He is not, as he rightly asserts, a Ceausescu. Nor have any of his opponents "disappeared". The very fact of the tribunal indicates that his legacy is not wholly tainted. But does that give him leave to think of his detractors as ungrateful pygmies, as he claims in the one sequence of fantasy megalomania at the end? Here the piece flares with sudden energy, which suggests that it would have been better conceived as a long monologue.

All silver-haired distinction, constantly aflicker between the urbanely humane and the ruthless, Malahide is better than the material. This is one of those plays where a trapped figure is visited by a series of interlocutors, here including the ghost of a former colleague and a woefully convenient student come to interview him for her term paper. The ur-drama is Oedipus at Colonus, and the spectre that haunts efforts in this field is TS Eliot's execrably inert Colonus update, The Elder Statesman.

I'm afraid Hinterland is nearer Eliot than Sophocles. It never establishes the necessary sense that Sylvester's virtues are inextricably intertwined with his failings. And the cogs of the political and the private just don't engage interestingly enough.

In rep (020-7452 3000)