If I were you: A pioneering new RSC play puts black people in charge

As part of their Yuletide programme, the Young Vic is presenting Ikrismas Kherol, a contemporary South African make-over of A Christmas Carol featuring a black, female Scrooge. The transposition of the Victorian original to the present-day world of Aids-ravaged and asset-stripped post-apartheid communities sluices away all trace of sugary sentimentality from Dickens' story of defensively hardened hearts and reawakened responsiveness to the plight of the needy. Displacement, by defamiliarising the customary, brings the moral truths of the piece closer than ever to home.

This technique is taken several steps further in one of the Royal Shakespeare Company's Christmas offerings, as Dominic Cooke stages his own adaptation of Noughts and Crosses, the novel by Malorie Blackman that imagines an alternative world where skin colours have been swapped round. The politically dominant race is black and the oppressed, second-class citizens are white.

Greeted with critical acclaim when it was published in 2001, Blackman's book was not the first work to posit a photographic-negative rethink of reality. Among its predecessors in this regard are White Man's Burden, the 1995 movie in which John Travolta plays a factory worker who is sacked and loses house and family as a result of a racially prejudiced mistake. As a result, he decides to kidnap the rich, black man (Harry Belafonte) who is top of the corporate heap. And in 1997 in Washington DC, Patrick Stewart starred as Othello in a production of Shakespeare's tragedy where the hero was the lone, white outsider.

Prejudice battens on binary division black/white, male/female, gay/straight, etc. Consequently, art is able to play this revealing reversal-trick wherever such simplified pigeon-holing and the resulting imbalance of power have turned pernicious. For example, the Martin Amis story "Straight Fiction" (from Heavy Water) is a crystal-clear-but-cross-eyed look at a late-Seventies/early-Eighties Manhattan in which homosexuality is the norm and heterosexuals are just emerging from the closet.

Noughts and Crosses is one of the finest of this reversal-ploy sub-genre. It refuses to patronise its audience with false consolation, pressing towards the tragic conclusion that's implicit in the material. At the centre, there's a teenage Romeo and Juliet-type couple a Cross (the ruling power) called Sephy, the black daughter of the deputy Prime Minister, and (two years older than her) Callum, a Nought (the underclass), the white son of her mother's sacked maid, who, after winning a scholarship, is one of the first tiny intake to the privileged kids' school.

Friends since childhood, the pair edge secretly towards fully fledged love. But, as the political situation darkens in this segregated society, there's the risk that the couple will cease to exist for each other except as representative figures in a brutal inversion of the status quo.

There are brilliantly arresting details in the play and the book that shock you into an examination of your unthinking assumptions. Injured in one of the scuffles with the protesters who want to keep the posh school blacks-only, a white girl is disfigured not only by the wound but by the "dark-brown plaster on her forehead which stuck out on her pale white skin like a throbbing thumb". When, in our society, whites call plasters "flesh-coloured", it's their own flesh to which they exclusively refer.

What is liberating about Noughts and Crosses, says Cooke, is that it focuses attention on "the forces that shape identity. It's a circular process circumstances shape perceptions which in turn shape circumstances." Early in rehearsal, he asked the black actors to share their experiences of the kind of everyday racism that often goes unnoticed by non-blacks. "They all had several examples that had happened just in the last week. I then asked three or four of them to direct the white actors in improvised scenes arising from this."

Cooke notes that the novel can keep the skin colours and the reversal under wraps until some way in. Adapting the piece for the three-dimensional world of drama, he had toyed with finding ways of "putting people off the scent" at the start but he has thought better of that idea as he's developed the play in rehearsal.

In the Travolta movie, the realisation that it is an alternative world steals up on the audience through incremental details like the programmes flickering on the TV at the white factory worker's house which are monopolised by black faces. However, White Man's Burden disappoints in its failure to suggest the historical background to the current situation.

By contrast, as Cooke says, the world of Noughts and Crosses plausibly knits together several ancestries: "there's the America of the 1950s, South Africa under apartheid, and in the handling of the Liberation Militia [rebel Noughts], the IRA of the 1970s and Eighties. It's remarkable how the story also speaks to people who have been divided on other than racial grounds."

Christmas is a propitious moment for the premiere of this adaptation. When people wish "Goodwill to all men", do they really mean "all"? Role-reversal art is a bracing reminder that to love your neighbour as yourself involves the spiritual heave of truly imagining yourself in your neighbour's position.