IN FREDERIC Mohr's one-woman play, a young Roman Catholic Irishwoman called Margaret Bulkley disguises herself as a respectably Protestant man called James Barry in order to become one of the most successful physicians in Victorian Britain. It sounds like a feminist flight of fancy yet, as so often with the suppressed history of women, the central facts of the story are almost certainly true.

Although there are dissenters who believe Barry was intersexed (a "hermaphrodite" in the old, politically-incorrect parlance), the widely accepted view is that Bulkley, the daughter of a well-to-do Irish family, emerged at Edinburgh University, aged 19, as James Miranda Barry. After receiving "his" degree, Barry became an army surgeon, eventually being promoted to the post of Inspector General of Hospitals of the British Army. "He" went on to become an early pioneer of Caesarean sections.

Mohr's drama, which was originally staged in the US and at the Traverse Theatre, Edinburgh, has not been seen in Scotland since it premiered in 1983. It has been revived by Borders-based Rowan Tree Theatre Company (which is currently celebrating its 21st anniversary), with actress Isabella Jarrett taking on the considerable challenge of the 90-minute monologue.

The piece is very much a play of two halves. In the first, we see Bulkley in Mauritius in 1819. She has, temporarily, thrown off her male disguise, though not through choice: she is pregnant. It is assumed that the child died shortly after Bulkley gave birth.

In the second part, set in colonial Canada in the late 1850s, we find Bulkley transformed - with the superb assistance of designer Gregory Smith - into the diminutive, somewhat gruff figure of Barry.

In truth, Mohr's work is barely a play at all. Rather it is a first-person narrative in which Barry's personal history is embellished and reimagined by the author. Although, in the second half, there is the artifice of Barry, the man, playing his male role before a group of his male peers, the script remains very much the retrospective telling of a story.

That said, the tale is full of fascinating facts and suppositions; from Barry's involvement in the dangerous, masculine pastime of duelling, to the mutual loathing between "him" and Florence Nightingale. She famously described Barry as "the most hardened creature I ever met throughout the Army". Mohr offers Barry some redress, providing him with a humorously hateful speech in which he derides "the cow" Nightingale.

The play's form - as a performed storytelling - may be self-limiting, but Jarrett deserves plaudits for a brilliantly sustained performance. One might question aspects of some of her characterisations (it seems unlikely, for example, that the privileged Margaret Bulkley, born and bred in colonial Ireland, would have spoken English with such a broad, working-class Irish accent), but the actress has mastered a substantial script in a manner which gives engaging expression to an extraordinary story from women's hidden history.

Touring throughout the Borders until February 9. Also at the Citizens' Theatre, Glasgow, from Tuesday to Saturday