Theatre: The King of Prussia; Donmar Warehouse, London

Here's an unexpected delight. As the first show in its short "Four Corners" season of work from Scotland, Ireland and Wales, the Donmar Warehouse has brought in a piece from Britain's fourth Celtic extremity - Cornwall. There are metropolitan sophisticates for whom the idea of community theatre has about as much appeal as a plate of Yorkshire pudding would have had for Proust. But I bet Kneehigh Theatre Company's production of the new Nick Darke play would leave them totally disarmed. This is community theatre not just in the sense of drawing its inspiration from the locality but also in the sense of offering audiences the rare and heartening spectacle of genuine, vibrantly eloquent company work.

Set in Cornwall and France in the late 18th century, this action-packed, racily written piece follows the fortunes of the eponymous King of Prussia. That's the sobriquet of John Carter, the leader of a local gang of smugglers. Played with charismatic dash by Tristan Sturrock, this figure falls firmly into the tradition of the likeable rascal who acts on the belief that breaking bad laws is a form of honesty. To hear him talk, you'd think smuggling was a mix of community service and job creation scheme. But his heart is in his words, as we see when he tries to recruit Mrs Stackhouse (Mary Woodvine), the bored wife of an upper-class botanist whose house just happens to have a tunnel connecting beach and cellar.

Mindful of all the parishes he helps to evade the punitive duties of this period, Carter is appalled when Milady declares a wish to sell the barrels of contraband cognac to her nob friends in Bath for a hefty profit. Repulsed by him, she makes an alternative deal with Charlie Barnicutt's hilarious Revenue man, whose stiff-backed incorruptibility swiftly turns to knock-kneed collaboration.

As you'll have gathered, this is a boisterous, jokey, inventively staged piece which dashes you round many a hairpin bend of plot, and glances irreverently at contemporary issues such as the rise of Methodism. You could see comparisons with the current predicament of the Cornish fishing industry, compelled to trade in "black" fish because of EC quotas. But if the play is saying that Carter's somewhat creative attitude to the law is justified, it does so with an impish grin, not a righteous frown.

Switching identities at lightning speed, the engaging cast of six populate a show that makes a virtue of simple props, an inclined deck-like central stage, and a strange object that rotates and mutates, now the guillotine, now a bowsprit. Lovely music begins and ends the piece, Mr Sturrock playing a mean Jew's harp. The show is a tonic, like a day at the seaside.

n Ends tomorrow. Booking: 0171-240 4882

PAUL TAYLOR