As Shauna Kanter's father lay dying, he muttered something about helping Brecht's family to escape. Years later, she found papers to suggest that this was more than just delirium. Now, she tells John Crace, she has turned her father's story into a play.

"I got Bertolt Brecht's kids out. They're alive and living in California. They're doctors." As deathbed confessions go, this one takes some beating. But since her father was prescribing himself large Martinis to go with the morphine provided by the doctors, Shauna Kanter just thought he was delirious and responded with a quick, "How nice", or some such banality. There the conversation ended. Within a few minutes her father was rambling about something else, and Ms Kanter thought no more about it.

Until five years ago, that is, when Kanter, a Jewish New Yorker, was 40. She needed some props for a play she was producing, and began rummaging through an old shoe-box into which she had shoved some of her father's belongings after he had died. Inside she found an old passport. Leafing through it, she was surprised to find that her father's name had been misspelt and that there was a visa for him to bring his wife and two children back into the US; as far as Kanter knew, her father's first wife was an American, so no visa would have been necessary; besides which, the couple had no children. To add to the confusion, his real wife, with the proper spelling, was listed under next of kin to be informed in case of death.

Further inspection revealed a missing photograph and a page heavily stamped with swastikas, showing that her father had entered Germany in 1939 via the circuitous route of England, Italy, Hungary, Turkey, the USSR and Poland. Since her father was a committed Communist, who had been imprisoned for his beliefs in the US some years earlier, it was highly unlikely he had visited Nazi Germany for a holiday. So, just what was he doing there?

Vague memories returned of her father telling her a bedtime story about being asked to help some German Jews, and Kanter began to wonder whether there might not be something in her father's dying words after all. It soon became clear that he couldn't have had anything to do with getting Brecht's family out - they left Germany in the early Thirties - but a conversation with one of her father's oldest friends made her realise that he must have helped to get someone out. "I found out that my father sometimes referred to his `two kids in California' [Kanter's family had always lived on the East Coast] and that he had paid for two German kids to go through medical school," she says. And this intriguing mixture of facts, half-facts and sheer invention has become the subject of Kanter's latest play, Legacy.

Kanter herself isn't the easiest of people to spend time with. It's not that she's unfriendly - far from it - but her eyes tend to fix you and her body seems to radiate an intensity that makes it difficult to relax in her company. In short, she's that most unfashionable of creatures, a political animal. These days, now that we're in the happy-clappy New Labour era, no one is really expected to care too much about anything. But Kanter does care and, like her father before her, she doesn't mind showing it.

She trained as an actress in New York and scratched a living for 20 years before quitting a Broadway hit in mid-run 10 years ago. "It was a shitty but very successful murder mystery," she confides. "But the management was so cheap that it couldn't be bothered to rehearse new people coming into the show, and I found myself acting with strangers who had no idea where they were supposed to be on stage. So I gave two weeks' notice and left to become a writer-director."

Her first play, Passing Through, which premiered at the avant-garde New York theatre, La Mama, was about three Israeli and three Palestinian women and the possibilities of reconciliation; her second, The Homecoming Project, drew parallels between the Highland clearances and today's absentee Scottish landlords. Not exactly easy viewing, then. And Legacy follows in the same tradition, interspersing a 1940s narrative with modern-day stories of racism and oppression as told by school- children; and if it seems to be a rather heavy-handed, not to say self-consciously Brechtian method of getting the message across at times, one has to admire the passion that drives it.

Unlike many of us in the Nineties who tend to see the Holocaust as a historical event, Kanter sees it as an ongoing experience that has still to be properly understood. Which isn't to say that she wasn't apprehensive about touring Legacy in Germany last summer. "I thought to myself: what right do I have to come and tell these people about their history?" she says. Yet she found there was a surprising willingness among young Germans to learn about the Holocaust. "Instead of being told about it by their teachers, they were keen to hear about it from Jews," she explains.

And Kanter found that, despite years of Holocaust education, many Germans still believed in a distorted truth: that it was only the rich Jews and the bad Jews who were sent away to the camps; that all the others left Germany of their own free will. The denial was so complete that many Hanoverian children were completely unaware of a Jewish cemetery just five minutes' walk from their school.

"Freedom from the past involves accepting the reality of what happened, and drawing a line under it," says Kanter. "Young Germans want to be able to take a pride in how much things have changed, but they can't as long as their history is kept so hazy." Yet she is no mere avenging angel out to rattle the Nazi skeleton in every German closet; she is as quick to point the finger at the Jews where necessary. "On our return, many English Jews simply didn't want to hear that we had a good time in Germany. They can't believe that the new generation has a chance to be different. They still hang on to my father's old tenets of `Don't buy anything German, don't study the German language, and never spend your money in Germany'."

Nor should one be too quick to label Kanter as just a Jewish political writer. Which is exactly what I was about to do after an hour's intense discussion of Jewish history. But as an afterthought I asked: "What's your next play going to be about." "Ooh," she said, with unfeigned relief. "Something light. A comedy." Preconceptions. Isn't that one of the themes of Legacy?

`Legacy': Cockpit Theatre, London (0171-402 5081). To 7 Feb