The Lemon Princess, West Yorkshire Playhouse, Leeds

At the point in Rachael McGill's compelling new play The Lemon Princess when 17-year-old Becky dies of Creutzfeldt-Jakob disease, there was a huge gulp of barely suppressed grief from the darkness behind me. This, after all, is based on the true story of a young girl whose life was cut off in its prime, an unhappy victim of the human version of bovine spongiform encephalopathy - mad cow disease. Names have been changed and some details fictionalised, but the focused way in which the story of her tragic death unfolds, the concentrated acting from this committed ensemble of actors, and the writer's sensitive handling of achingly raw material, only add to its enormous impact. The people who went through the emotional and physical hell that is being described on stage are sitting alongside us. All except for Becky.

At the point in Rachael McGill's compelling new play The Lemon Princess when 17-year-old Becky dies of Creutzfeldt-Jakob disease, there was a huge gulp of barely suppressed grief from the darkness behind me. This, after all, is based on the true story of a young girl whose life was cut off in its prime, an unhappy victim of the human version of bovine spongiform encephalopathy - mad cow disease. Names have been changed and some details fictionalised, but the focused way in which the story of her tragic death unfolds, the concentrated acting from this committed ensemble of actors, and the writer's sensitive handling of achingly raw material, only add to its enormous impact. The people who went through the emotional and physical hell that is being described on stage are sitting alongside us. All except for Becky.

Scenes of the most depressing nature are leavened with humour, some of it very funny and some of it very tasteless (though no less acute). As was the case in real life, Becky's dad is a stand-up comedian and the play is framed by some of his routines on the northern club circuit, with gags contributed by Richard Stacey. Humour is a great relief, and without it this devastating tale of procrastination on the part of unsympathetic government officials, the ulterior motives of a tabloid out to buy an exclusive story, and the effects of coping with terminal illness would make for a far grimmer evening.

It was the director Ruth Carney who had the idea of making a drama out of this personal yet also very public crisis, with the co-operation of Becky's family. Into the story of Becky's illness and her father's gradual loss of hope, McGill has spliced scenes from the subsequent inquiry into what went wrong with official procedures in recognising the appalling threat posed by vCJD. Sometimes the switches between the domestic narrative and the formal investigation are scrambled, with barely seconds between them. But there are great lines for all the characters, and the nimble way in which the cast of five handles its various roles is breathtaking.

Ian Reddington is a bundle of optimism and courageous determination as Becky's widowed dad - there can't be many roles that involve doubling up as a po-faced government minister and jokey stand-up comic. Elaine Glover is painfully convincing as the carefree teenager-turned-debilitated victim, but the portrayal of her little sister, played with uncanny insight by Samantha Robinson, is a real show-stealer.

The frustrating freezing-out by official funding bodies of local scientists beavering away to find a cure is contrasted with the apparent callousness of American scientists experimenting on Becky with the hazardous drug Quinacrine. The refusal by people, who should have known better, to acknowledge potential problems in the food industry (remember the then agriculture minister John Gummer feeding beefburgers to his daughter?) is just part of the increasing gulf between what people need to know and what the government makes public. And though the origins of this play are in the north of England, the issues resonate throughout the country. The Lemon Princess (the affectionate name her dad coined for Becky after jaundice fatally attacked her) deserves repeated airings before as wide an audience as possible.

To 5 March (0113-213 7700)