If Richard Nixon were alive, he might be pleasantly surprised to see how well Stacy Keach has treated him in Peter Morgan's riveting "Frost/Nixon."

Gone is the stooped, shambling walk, gravelly voice and shifty-eyed gaze that Frank Langella used to such good effect in the similarly riveting film. After all, the camera is made to capture an actor's face, body language and all those psychological tics that frequently define a character far better than words.

But this is stage, and Keach has opted for a different Nixon: bulkier, for one thing, and not so easy to kick around anymore — less of a paranoid type and more the battle-hardened old warrior gearing up for a final, grand fight to the finish. Keach goes so far at times as to make Nixon amiable, almost ebullient, with a spring in his step and what passes for a twinkle in his eye.

It works beautifully. It might not be the Tricky Dick some people remember, but it's a fair approximation of someone like him, who hasn't yet hardened into caricature. Langella gave Nixon a soul, but Keach gives him a personality, and it's a tossup as to which was more difficult to accomplish.

The play also works because Morgan knows how to write about powerful people forced to reveal themselves — for better or worse — under great pressure. In this case, he's fortunate that the four televised interviews followed such a useful dramatic arc, with Nixon taking David Frost to school in the first three but flunking his finals badly in the fourth and only test that mattered: Watergate.

Alan Cox as Frost holds up his end of the match just fine. Two more unlikely opponents would be hard to imagine than the cerebral, grind-it-out, reclusive Nixon and the slick Brit, with his flashy lifestyle and obvious enjoyment of the company of other people, especially of the female persuasion. Cox almost dances the part at times, barely able to contain the ambitious energy coursing through his trim body.

The staging by Michael Grandage, who directed the play in its original London incarnation, is spot-on. The pace is brisk, the supporting characters sharply defined, and Jon Driscoll's gridlike video design is a perfect fit for the final close-up of Nixon's defeated face, seeming to put him behind bars in a prison of his own making.

Two complex yet exciting hours without intermission rarely have gone by so fast.