The American playwright Wallace Shawn doesn’t think theatre is worthwhile unless it makes you squirm at least a little bit, and The Fever, a disturbing monologue which he first played at the Royal Court himself (in the Upstairs studio in 1991) certainly gets under your skin.

Well, it got under my skin in Shawn’s performance and it certainly does again in Clare Higgins’ riveting account on the main stage. The one character is really a sort of disembodied voice of the author saying what he really thinks about being a pampered middle-class liberal holed up in a hotel in a small country with a war going on outside.

The traveller, in this case Higgins, describes an execution she knows is happening that morning. It’s as if she’s there. She then drifts in and out of memories and dreams, making connections between the poor and the privileged, re-defining the philosophy of Karl Marx, wondering why anyone should weep for a Chekhov character who is leaving a cherry orchard to live in a Paris apartment, recalling childhood slights and fears.

Higgins is simply dressed in a crisp white blouse and blue jeans. Director Dominic Cooke allows her a chair to sit on, a water cooler to drink from and a huge packing case to lean against. Otherwise the stage, lit by Jean Kalman in three distinct passages of time, is bare, scenery piled up to the side, back wall visible, a ladder leaning against it.

It’s not so much anti-theatre as naked theatre, a very different thing. Shawn first performed the piece in private Manhattan apartments to small audiences of friends. Higgins brings the full armoury of her acting technique to suggest something less quizzical: the tragedy of helplessness and the need for minor consolation at all times.

She rings various vocal variations, colouring the wonderfully supple prose with sudden bursts of anger and even oratorical flourish, especially in the chilling insistence that, should the poor take over, then they must do so with morality, not violence – or they’ll be shot.

The play somehow incorporates political hypocrisy into the stew as well, even as it reveals a mind perturbed by the impossibility of taking positive action that means anything while luxuriating in the pleasures of art and clean bed linen. It’s a brilliant play and a great start to the three-month Wallace Shawn season in Sloane Square.

- Michael Coveney