Sometimes in the theatre you know in the first half-minute that you're getting your hard-earned twenty quid's worth. That's how I felt as Alan Cumming descended from on high, upside-down and bare-arsed, to wink at the audience and proclaim 'So Thebes. I'm back.' A moment of theatrical magic, exploited to the full. But the important thing about Cumming's performance is that it isn't just a high-class piece of camperooning about in a gold lame dress. The nudge-nudge, wink-wink complicity with the audience has a serious dramatic purpose. We're drawn into a relationship with this outrageous Dionysus character and we're rooting for him as he clashes with the buttoned-up Pentheus, king of Thebes, who disapproves of all this sex, drugs and rock and roll on mountaintops. We, being a hip audience at the Lyric Hammersmith, have a good laugh at the expense of Pentheus, who appears to be a repressed Scottish Calvinist. But in the second half of the play comes the payoff. The action dissolves in a pool of blood, and Agave, the mother of Pentheus, comes on stage streaked in gore and proudly bearing the severed head of her son, which she thinks is the head of a lion. Suddenly Dionysian sex, drugs and rock and roll don't seem quite so much fun after all. Dionysus destroys everybody in Thebes, not only those like Pentheus who resisted him, but those like Agave and grandfather Cadmus who were tempted to become his followers. This is a stunning production by John Tiffany, who gave us last year's Black Watch at Edinburgh. I like David Greig's version of the play, perfectly suited to Cumming's androgynous talents. Cumming gives us not just the camp humour but the sinister, malicious spirit of Dionysus as he seeks his revenge on the city that has driven him out and dishonoured his mother. This god is more of a serial killer than a cuddly Graham Norton, and if we had watched him more carefully at the start we would have realised it. It's a chilling play, which I have seen only once before in Peter Hall's National Theatre production with Greg Hicks a few years ago. I found that impressive, but a bit OTT. I really liked this show, which should do wonders not only for the National Theatre of Scotland but for the ancient Greeks. My only reservation concerns the music and lyrics for the chorus, performed by eight black women in blood-red dresses. The mixture of gospel, rock and roll and other styles occasionally misfires and I just didn't feel that Tim Sutton's music reached the level as the rest of the production.