THEATRE Road to Mecca The Royal Exchange, Manchester

Ferdinand Cheval, a postman in 19th-century rural France, walked many more miles each day gathering stones, and over 33 years built his "Palais Ideal", a beautiful and utterly idiosyncratic structure of no practical use whatever. The historical heroine of Athol Fugard's The Road to Mecca, Helen Martins, was evidently a similar figure. Living alone in a remote village in south Africa's Karoo Desert, she turned her house into a personal "Mecca" of sculpture, ornament and light using such materials as beer bottles ground in a coffee-mill. Such figures are compelling for the utter purity of their vocation, artists indifferent to reputation, absorbed only in the mystery of their creativity and the human freedom it represents.

Creativity, freedom and their relationship are Fugard's subjects in his account of Helen Martins. When we meet her, in old age, she has become more and more withdrawn, but this is South Africa and even in the Karoo there is no sublime isolation for the artist or anyone else.

She is befriended and beset from two sides. Her young friend Elsa, whose flying visit from Cape Town is the play's occasion, is the urgent, anguished voice of white liberalism. Marius Byleveld, the local pastor, steely and erect, is the embodiment of austere Afrikanerdom. It is the measure of Fugard's profundity as a dramatist that he makes our sympathies and antipathies towards these characters so complex. The bravery of Helen Schlesinger's performance as Elsa lies in how unattractive she is prepared to make her character. Politically impeccable, and in desperate turmoil in her personal life, her self-absorption and impatient hectoring of Helen can still make her unbearable. Conversely, William Russell as Marius must find the man down from the pulpit. This I think he does not quite do, but the modulation in Marius from sermonising to acknowledgement of his own desolation is subtle and difficult to catch.

As the excellent Ann Mitchell scutters about in her housecoat, it is at first hard to recognise the significance of the apparent bric-a-brac and dozens of candles that surround her. Her eyes start warily and she flinches before both her visitors. She is at bay: the long pressure of the community against the non-conformist now urging her to move into a home, Elsa exhorting her to an heroic stand. It is not hard to see Fugard's 1980s dilemma as an artist caught between government oppression and the demands of "the cultural struggle", but what an ambivalent emblem Helen is. In Cape Town, Elsa says, they talk about freedom all the time without knowing what it truly is. She thinks Helen's idiosyncratic defiance and her art makes her truly free, but we might also see her as distant, "irrelevant". None the less, out of her candles and bottle-glass comes light, which "is harmless and only wants to play".

Director Gregory Hersov's addition of the anthem "Nkosi Sikele" - gently enough to avoid any simplifying stridency - movingly underscores this affirmation as it closes this powerful production.

To 29 March. Booking: 0161- 833 9833 Jeffrey Wainwright