THEATRE Slaughter City, RSC Pit, London

Naomi Wallace's blood-stained account of American industrial relations offers large dollops of symbolism, but no slice of life.

You can't accuse Naomi Wallace of malingering in the one milieu. Her last couple of plays, for example, have transported us on Gulf War flashbacks (In the Heart of America) and to a boarded-up London house during the Great Plague of 1665 (the excellent One Flea Spare). Slaughter City, now premiered in Ron Daniels's Pit production, deposits us in a US abattoir, designed to offer a symbolic microcosm of the pernicious relations between capital and labour. The set is as bloody as a butcher's apron. Carousels of realistic-looking carcasses swing by on hooks. Innards are rummaged out. Gristle is sliced from bone. These must have been testing times for any herbivores in the RSC's scenic and props department.

But though the setting of her plays may be varied, a strain of repetitiveness can now be detected. In In the Heart of America, the confused ghost of a Vietnamese woman searched for the murderer of her three-year-old daughter in a world where, after US action in Panama, Grenada and Operation Desert Storm, parallel post-mortems were taking place. The implication, highly tendentious, was that all American wars are, at some level, the same: a repeat of the My Lai massacre.

Slaughter City applies that formula to the history of injustice, negligence and disaster in the field of American industrial relations. Here, the perplexed figure who wanders in from the past so as to point up the debatable theme of endless recurrence is Cod (a signally intense Olwen Fouere). Her mother, a turn of the century textile worker, had had to jump to her death from a fire but managed to save Cod, still in the womb, by making a last-minute pact with the Sausage Man (Robert Langdon Lloyd).

With his grinder turning disgusting refuse into profit, this figure emblematises capital, but he evidently has supernatural powers. The price of saving the child's life is that she become his "spark", to be sent wherever he chooses for ever. He seems to revel in Cod's resistance to him, "the labourer against my system! It's glorious, it's heroic. And we have all the time in the world..." To him, it's a game he thinks he can't lose; to her, it's like a recurring nightmare as, in male disguise, she's taken to be a witness- participant in one industrial horror after another.

Slaughter City ends with her breaking the cycle and taking effective action in the here and now. You may wonder, though, whether that inspirational close compensates for the drawbacks of giving the piece a cumbersome, far-fetched and confusing mythic element that raises more doubts than it resolves. Cod's co-workers are splendidly played by Lisa Gaye Dixon, Sophie Stanton and Alexis Daniel and there is, at times, despite an overdosing on meat metaphors, a hard-edged particularity in the writing. I'd have preferred to find out more about their lives instead of being shown the pattern of which they are allegedly part. And that pattern is simplistic. The boss (Linal Haft) has a pet which is the single last surviving snail of its kind. I bet you can't guess what happens to it and him. Well, talk about asking for it.

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