It's common, even expected, for Edinburgh Festival successes to lose their shine in London. Not in this case. Terre Haute comes to the Trafalgar Studios via a national tour still tight with the strange, sad tension that made it a hit up north last year.

Its central idea is immediately compelling. Inspired by a correspondence that apparently happened between Timothy McVeigh, the Oklahoma bomber, and Gore Vidal, the great, gay American man of letters, it places ringers for those two men into a secured conference room and watches as frictions build and sparks, sexual and emotional, look set to fly.

Arthur Darvill's Harrison, the bomber, stands in a gauze prison, besides which Peter Eyre's James sits, a political polemicist determined to get inside a man who claims to have killed out of political protest. Harrison, of course, saves the best details until last, and, inevitably, is keen to turn the questions upon James himself.

In this way we see into these two slightly lost souls. Drawn towards his subject's rough looks as much as his sharp, untrained mind, James plays both gentle uncle and condemnatory father figure, working for the root of Harrison's reasoned psychopathy. Eyre has a melancholy, genteel effeteness behind which, we are convinced, a cunning interviewer's mind is ticking like billy-o.

Darvill's Harrison is his equal. His nervy performance shows us a man of brute intelligence desperate for an outlet. One minute he is a caged beast, the next a cynical propagator of his own myth, the next a knowledgeable and even flirtatious student to James.

When the men are apart, he paces his cage and hugs himself. When they are together, the air hums with suspicion, attraction and, at times, shared indignation at a world which has felt the force of one's essays, the other's bomb.

Edmund White's play has elements of contrivance - in referring to other events, such as Waco, he has the men spiel off facts to each other which both already know to provide the poor audience with background. That feels obvious. Yet his command of sub-text is fine, and these wonderful actors play to it.

As the play draws to a close and Harrison awaits execution, James remarks genuinely that, were it not for the bombing, Harrison would be a nothing. Harrison agrees, but one look at his face and the heart weeps for him. Beneath the bravado, he knows he is nothing anyway.

• Until 2 June (0870 060 6632). www.theambassadors.com/trafalgarstudios.