Arcadia, Old Vic, Bristol

If you want a seriously brainy whodunit, look no further than Tom Stoppard's Arcadia.

If you want a seriously brainy whodunit, look no further than Tom Stoppard's Arcadia. When it opened in 1993 it was hailed as a masterpiece by some and accused of being too clever by roughly two and three- quarters by others. But whatever it is thank God for its steady stream of puns, quips and jokes. You need them to assuage the brain- ache caused by the play's discussion of, among other things, Fermat's last theorem, entropy, chaos theory and nasty little blighters called iterated algorithms.

This vaudeville of gags and higher mathematics is shoehorned into a literary detective yarn set in a Derbyshire mansion in the early 19th century and the present. Thomasina Coverly, a mathematical prodigy, is having classes from her young tutor Septimus Hodge, a school friend of Lord Byron's. The date is 1809. Also milling about are Thomasina's sexually charged mother Lady Croom, a very minor poet called Chater, and a fawning landscape gardener of the picturesque style. Byron remains off stage but very much around.

The present is represented by the Coverly descendants. When not stroking his tortoise, young Valentine is working on mathematical formulae for predicting grouse populations on the estate while a brace of modern scholars poke about his ancestral home. Hannah Jarvis - an expert on Lady Caroline Lamb - is researching a hermit who might at one time have lived in the garden. A sleazy Sussex don and Byron expert called Bernard Nightingale tries to prove that Byron shot Chater in a duel and then fled to Lisbon.

All this Jane Austen-era costume drama is acted out on Stephen Brimson Lewis's elegant windowed set as the scenes flit back and forth from past to present. I doubt whether many of us will remember the maths in this by the time we reach the car park afterwards. But Stoppard generously allows us the illusion of following it by putting the big universal questions out on the kitchen table - such as why a coffee cup goes cold and not hot if you leave it and why jam once stirred into a rice pudding is impossible to unstir.

There's a lot of more upmarket explanation of chaos theory - but for me Stoppard does this less well than Jeff Goldblum managed in Jurassic Park. The play is perhaps best when it puts down the blackboard chalk, so to speak. Septimus's beautiful speech on the lost works of Aeschylus and burnt libraries (saying it is of no consequence what we have lost because all things are eventually re-made - "we shed as we pick up") strikes me as the heart of the play's decent, humanist spirit.

Rachel Kavanaugh's enjoyable production is well acted. Blake Ritson is superb as the tutor Septimus in charge of the precocious Thomasina (Loo Brealey). As the desperate don, John Hodgkinson spars hilariously with Hermione Gulliford, excellent as the head-screwed-on author Hannah. Only the usually superb Amanda Harris seems off-form as the haughty Lady Croom.

To 16 October (0117-987 7877)