Halfway through this play a woman from the audience burst into tears and ran out of the theatre shouting, "It's sick, I can't believe you're all laughing at this."

Everyone else froze. Onstage Gus Brown as Stuart White, a tasteless gameshow host leading an audience quiz peppered with bad jokes about immigration and poverty, looked shaken.

Stuart had been "interviewing" a security guard who found a body in his supermarket car park.

The Pakistani man had fallen from a plane after hiding in the wheel bay in an attempt to escape slave labour in Dubai.

The audience were playing "Problems Puzzles Puzzles Problems" and winning points by guessing how long the man might have survived in the airless hold.

The woman stormed out as Stuart held up a bag of what purported to be the man's brains. We felt like collaborators.

After the interval, she was back, as part of the play, revealing herself as one of the company.

All political theatre should challenge audience perception.

By presenting something the audience believed to be real, Cardboard Citizens crossed the gulf between a play set in its own artistic bubble to something about real people, in the real world outside the theatre.

When middle-class suburbanite Hattie, played by Karen Paullada, has a big strop about forgetting to cook the beef for Sunday lunch, her plight is juxtaposed against that of a Albanian asylum seeker who cannot feed his family.

Visible is traditional agitprop: Theatre that aims to change the world, with its Brechtian placards and songs and a slide show of images of consumerism and poverty, from Barbie dolls to flycovered children.

Often uncomfortable, sometimes funny, at times it was plain bizarre. The first scene, a kitchen sink drama about an unhappy couple, was followed by a giant penguin, rabbit and bear bounding in to direct a singalong.

At the end we were told: "If you feel you've been affected by any of the issues in tonight's performance, do something about it."

The message, that the way wealth and citizenship are distributed is grossly unfair and our actions affect those we will never meet thousands of miles away, is perhaps nothing we don't know already.

Perhaps if we hear it often enough by such powerful messengers, we will.