Frost/Nixon, Donmar Warehouse, London

David Frost's televised encounters with the disgraced former president, Richard Nixon, pulled in a record audience for a series of news interviews when they were aired in 1977.

Now Peter Morgan has created a shrewd, partly speculative stage play about a contest in which the British talk-show host eventually extracted an apology (if only for "mistakes" rather than crimes) from the man who had discredited the presidency and left his country in trauma through his corrupt efforts to cover up the Watergate Scandal.

Frost/Nixon, a sharp, witty and haunting production by Michael Grandage, might appear to be a somewhat paradoxical venture. Not only is it the first foray into the theatre by a writer noted for his excellent TV dramas, which include The Deal (about the troubled relationship between Blair and Brown), but television would, literally on the face of it, seem to be the ideal medium for this subject.

As Nixon, portrayed in a performance of reverberating, near-tragic depth by Frank Langella, remarks to Frost during the negotiations, "television and the close-up, they create their own set of meanings". There's no actual correlation between a perspiring upper-lip and guilt, but TV summarily enforces one.

So it is frustrating that during the early bouts, the bank of monitors above the live action gives us roughly the same long-shot perspective on the proceedings that we see on stage. Even when Frost and his team try to analyse how Nixon has been outmanoeuvring them, we can't see the duelling as it was transmitted on television.

By contrast, in a highly effective sequence, we are permitted to scrutinise in close-up Frost's own discomfiture when grilled by his CBS rival, Mike Wallace on Sixty Minutes, about the questionable ethics of giving Nixon a hefty fee.

But the play and production are tactically saving themselves for the climatic showdown when, emboldened by damning new evidence unearthed from the White House transcripts by a zealous member of his team, Frost, an eerily affable and ineffable Michael Sheen, breaks through Nixon's defences. Then you get the best of both worlds: the immediacy of theatre and the camera moving in on the ex-President's stricken, self-loathing face.

Frost/Nixon tries to establish that while the two title characters, are in many ways, decidedly dissimilar, the pair have profound underlying connections. Both are presented as desperate for rehabilitation - Frost's US show had recently been axed - and as humbly-born folk driven by the need to prove themselves.

To drive this home, Morgan even imagines that a tipsy Nixon might have phoned Frost on the eve of the final encounter in a call in which he unsettlingly identified with his adversary. If this is not credible on any level, there can be no doubt of the timeliness of a play that shows us a president who feels that, by virtue of his position, whatever he does is legal, if he deems it to be in the interest of national security. A canny, flawed, and fascinating piece.