If you don't like the US, you might like Fallujah. Sometimes, this piece of documentary theatre seems more interested in fomenting anti-Americanism than in informing its audience. In the context, that is understandable.

Less tolerable are its theatrical deficiencies, which render a confusing situation still more baffling, and try the patience of even the most sympathetic on-looker.

The siege of Fallujah stands as a low-point among the many troughs of the Iraq war. Three years ago, occupying American troops fired on a crowd of civilians, killing 13. Large-scale rebellion followed. American troops pacified and recaptured the city at the cost of a large number of civilian lives.

The exact number and the extent to which deaths could have been avoided are still in dispute. Fallujah, compiled by Jonathan Holmes from witness statements collected by Dr Scilla Elworthy, doesn't help much.

Performed in promenade on a large warehouse floor cluttered with installation art, it is hard enough getting into position to see the actors, let alone judge their testimony. As Harriet Walter's journalist Sasha tears around the place and into the US generals, you hope she'll stop for a moment and get the basics of the conflict straight.

Denied factual context, the audience is at least in a mental state to reflect the uncertainty of war: bombarded with suffering without the chance to trace causes and effects.

Still you can't help but notice that all the American soldiers are idiots, and the few Arabs lovely and reasonable. US atrocities are relayed in secondhand reports, lovingly invested with emotion by Imogen Stubbs's aid worker.

US claims that insurgents were using civilians as human shields go uninvestigated.

And it's so earnest. Yes, we are talking war crimes here - but there are a few moments in the script clearly intended to provide humanity and light relief.

They stand no chance performed over Nitin Sawhney's constantly droning, portentous soundtrack.

And it's long - well over an hour and a half on your feet. No human rights breaches there - but why add more lumbar pain to the world for the sake of trendy staging?

• Until 2 June. Information: 0870 162 0295. www.Fallujah.co.uk