Theatre ONE DAY IN OCTOBER Riverside Studios, London

Here's the story: a young woman disgraces her distinguished family name when she conceives a child by an unknown lover. However, in the throes of childbirth she names a soldier and her uncle, in whose house she resides, tracks down the man and demands he do the decent thing. But the soldier - a young man of impeccable background and reputation - denies ever having met her; meanwhile, the butcher's boy comes forward to confess to having, as it were, delivered the meat, and offers to be bought off at a reasonable price.

The bones of George Kaiser's 1927 drama, now receiving its British premiere at the Riverside, would make a respectable Feydeau-esque farce - possibly the provincial French setting and the extreme bourgeois respectability of the characters are meant to point expectations in that direction. Dana Fainaro's production for Generation X theatre company certainly plays up the story's farcical elements, and the evening is shot through with mild drollery - much of it coming from the intense formality of manners and language.

Really, though, this is a tragedy about the conflict between imagination and reality. It emerges that the soldier has met the woman before, or at least come across her, on the October day of the title, when he spent half a day in her home town waiting for a connecting train. A series of chance encounters, of which he wasn't even aware, have been construed by her as a form of marriage: they happened to glance at some rings in a jeweller's window at the same moment; at a church service they knelt next to each other to receive the sacrament; and they sat in the same box at the opera. The soldier not only falls in with this version of events, he is even prepared to accept that he is the child's father, even though the objective evidence points to his having been on a train at the moment of conception. He rejects the butcher's boy's story and refuses to let him be paid anything.

The play's switch of tone (matched by a change in the incidental music, from Brahms to Second Viennese School) makes it hard to place - it certainly isn't what you expect from a leading German Expressionist (the closest parallel, in the way it collides love and death, reality and imagination, is Lorca's Don Perlimplin). Are you meant to take it as idealist meditation on the nature of reality? Or as political satire? Certainly the butcher's boy, with his handy grasp of practicalities, is an oddly Brechtian figure; and it's notable that he comes to grief only when he allows himself to be caught up in the fantasies of his social superiors.

Fainaro's production doesn't offer many clues, but the uncertainties are compensated for by Paco Delgado's clean design and some strong performances, particularly from Michael Begley as the sweating, servile butcher's assistant. If it doesn't persuade you that this is a major European classic, it does suggest that Kaiser is worth a long, hard look.

n To 7 Oct. Booking: 0181-741 2255