THEATRE / The finger of suspicion: Jeffrey Wainwright reviews an adaptation of The Moonstone at the Royal Exchange, Manchester

AFTER a while, the mind starts looking for amiable distractions. Here, Mr Betteredge's grog-jug came to the rescue not only of the distraught Franklin Blake, just back from a nasty experience on the quicksands, but of this reviewer as well. Solid, endlessly serviceable, even elegant in an utterly unpretentious way and providing a satisfying clunk on a deal tabletop, it might even be seen as the very emblem of the 19th-century novel. I think people might go to see theatre versions of books like The Moonstone just to catch sight of such utensils.

Meanwhile, a plot was going on. A huge diamond, the moonstone, nearly as big as the grog-jug, though less impressive, has been stolen. Enter Sergeant Cuff. If that wig is supposed to make him look like Helen Mirren, it isn't working. Who are the suspects? Well, there are three Hindus who happen to have been passing this country house posing as jugglers, and the diamond was stolen long ago from a Hindu temple. There is a chap called Murthwaite conveniently on hand to explain a lot of this background to the assembled drawing-room - the caste system and so forth. But the Hindus are made to look and behave like Wilson, Keppel and Ram Jam Singh so it's hard to see them as serious swishers, even when they produce knives from their turbans yet more fearsome than the hatpins frequently unsheathed on this stage. But I liked Ezra Jennings' hat, not quite a stove pipe, but more undertakerly than medical and with a mossy blue to it. Raad Rawi wears it on top of his spindly frame as he comes with a laudanum lope into the plot, and provides in his two scenes all the spine-crawling there is. As Betteredge, George Malpas doesn't have a hat but his wonderful white beard is a wistful reminder that it's Christmas outside. He is the opposite bookend to Rawi's Jennings, and his distinctive version of the wise and gravelly old retainer props up the show from the other end.

Among the several unfavourable reviews Wilkie Collins received on the 1868 publication of his detective story was one that thought he must be 'weary of his own occupation, and puts together the pieces of his puzzle with little trouble and no interest'. While I would not want to go so far in describing this Royal Exchange adaptation of his novel, it does have an unexcited, routine air to it that is hard not to associate with the company's regular strategy in solving its programming puzzle. Could it be that the familiar formula of the workmanlike transposition of favourite novels, glossed with lavish casting, tasteful design and sharp effects, has begun to bore its practitioners nearly as much as it does many of the theatre's regular audience? The effects are sometimes good here, at least in the shifting sands devised by David Millar (design) and Vince Herbert (lighting). But when one catches oneself scrutinising the dark recesses of the theatre's roof to anticipate some welcome diverting coup, something is amiss on the stage below.

James Maxwell has excelled at adaptation in the past - notably his version of Pride and Prejudice a few years ago - but this show lacks all tension where it should be strongest, in the plot, and does nothing to animate the cardboard characterisation. The Christmas production is always one of this theatre's main attractions of the year and is properly given the resources to match. On this occasion, these have gone down the show's abiding and appropriate image: the glugging vortex of those shifting sands. Pass the grog.

Runs until 30 January. Box office: 061-833 9833