Flesh Wound, Royal Court Upstairs London

First nights at the Royal Court Upstairs are getting a bit too much alike. At the last one, seated in the first row, I had to cover my eyes while one actor did something revolting to the other's hands. This time, sitting in the same spot, I made the same gesture, for the same reason - not, as it turned out, a wise move, for, a moment later, a knife with an eight-inch blade flew across the stage and whacked me in the ankle. Well, I once panned a novel by Jeanette Winterson and I'm still here, so I guess I just lead a charmed life.

I'm sure the actors had no intention of inflicting the mark of the title on the customers, but in another respect the name of Ché Walker's drama is all too appropriate. Though a lot of blood flows, the play never cuts very deep or hits anything vital. Instead of dramatic movement, there is simply tergiversation. The author piles on the switches of loyalty and judgement until what little credibility the play has is thoroughly shredded.

Joseph, a tough guy even in the brutal, drug-ridden north London neighbourhood of Somers Town, alternately wants to give his long-lost son "the cuddle I've been storing for you for 20 years" and to break his neck. Vincent likewise flops between submitting to the paternal embrace and threatening to blow out dear old dad's brains. Faced with the wild-eyed Vincent waving a pistol, Joseph says, with the understatement native to all Englishmen, "I suppose I shouldn't have come."

Their confrontation takes place in the tower-block flat of Vincent's half-sister, Deirdra, a girl with a practical approach to crises (when Vincent prepares to shoot Joseph, she lies down in the bathtub and covers her ears) but an unfortunate habit of provoking them. Vincent, in a typically brainy move, has raped a local hoodlum's retarded sister and needs bullets, so, even though Deirdra has screamed the place down denouncing violence, she obligingly pops out for a few. What sends her out the door, though, is really the playwright's need to have Vincent and Joseph alone so they can change their minds again. "Bloodshed's all that's left now," Vincent declares, speaking not only for his desperate character but for author, who has no other way of creating dramatic excitement.

As Joseph and Vincent, Michael Attwell and Andrew Tiernan, respectively, give adequate performances; Tamzin Outhwaite, as Dierdra, does not rise to their level, her uninflected snarling defiance making the character even more boring than she is on paper. Director Wilson Milam may have been attracted to Flesh Wound because of its superficial similarities with his great success The Lieutenant of Inishmore. In both plays, the characters' emotions are limited to anger hot and cold and drooling sentimentality. Martin McDonagh, however, also lets them show love and idealism, however misplaced, and he has better control of structure and tone - you never wonder whether the laughs are intended. Here the dialogue is so ludicrously thick with "authentic" slang that it sounds like a lesson in underclass for beginners.

To 7 June (020-7565 5000)