The Merchant of Venice, Courtyard Theatre, Stratford-upon-avon

It's not the word that instinctively comes to mind but, technically, The Merchant of Venice is a comedy. Tim Carroll's version for the Royal Shakespeare Company reminds us that the play is about three loving couples, that it contains a lot of romantic mischief, and that it ends happily – at least, for everyone nice.

Georgina Rich's Portia, though rather drab, gets plenty of laughs as she slags off her suitors, and even more in the triumphantly comic final scene, when she and her maid (a droll Amanda Hadingue) pretend to have cuckolded their errant husbands. William Beck, by turning Launcelot Gobbo into a young Nicky Henson with a touch of Boris Johnson, has made that usually unbearable clown a highly enjoyable one.

Yet there is that bit of unpleasantness about a business deal gone wrong. Carroll minimises it by giving us, in Angus Wright, a Shylock who, in this modern-dress production, is not just a dark suit but an empty one. Bland and cool, he keeps a casual hand in his pocket during most of the "Hath not a Jew eyes?" speech – a gesture of indifference favoured by most of the men in this youthful cast. This Shylock is only mildly annoyed when his daughter elopes with a Christian, when he prepares to drive his knife into Antonio's breast, and when the Duke of Venice decrees that he be stripped of his wealth and religion. Nor is he remotely Jewish.

The most passionate character is the Gratiano of John Paul Connolly. Hearty in fellowship, he cries, with equal heartiness, for a rope round the neck of Shylock. A bit more emphasis in this vein could have made the play a damning judgement on its jolly chaps and clever girls but, as it is, we are asked to side with the guests at the genial country-house party in Belmont.

Laura Hopkins's design contributes to the rootless, weightless mood by setting the casket scenes in a fantasy cavern. Carroll's larky manner has its merits, but what price a Merchant without Shylock? The Jew's hand may be stayed, but this director has taken a knife to the play's beating, bleeding heart.

In rep to 27 September (0844 800 1110; www.rsc.org.uk)