Preview: Flat Stanley, West Yorkshire Playhouse, Leeds

"The story is simple," says Mike Kenny, who has adapted Jeff Brown's much-loved children's book Flat Stanley for the stage. "A noticeboard drops on a boy during the night and he's flattened."

Flat Stanley, written in 1964, is a US cultural icon, appearing in TV shows such as The West Wing. Kenny, an acclaimed children's playwright, has adapted the first stage version of this classic tale for its world premiere at the West Yorkshire Playhouse. The plot centres on inch-thick Stanley Lambchop, who can go to places ordinary boys can't.

"The story is like Metamorphosis for children, but with the opposite effects, as both Stanley and his parents take his flatness in their stride," says Kenny.

At first, it's great fun for Stanley, getting posted to California and being flown as a kite. But then the novelty wears off and Stanley begins to wish that he was like other boys.

"By the end, he's sick of being flat, and he's gone through the arc of celebrity," says Kenny. "He's foiled a museum robbery and has become famous. But after a while, there's a backlash. People start calling him names in the street and pointing at him."

Kenny, who has worked on productions for audiences with learning disabilities, points out one of the book's key themes. "It's a metaphor for difference or disability," he says. "But I don't want to overplay that aspect - it makes it sound terribly worthy."

The production has been a technical challenge. There are nine different puppet versions of Stanley, and they're all operated by one man, Stuart Cairns, who has just finished pulling the strings on a touring production of Stuart Little. "As soon as the puppet moves, you start to relate to it like a human being - it's very odd," says Kenny. There are also plenty of songs, sung by a strong cast that includes Lisa Howard and Robin Simpson.

"There's nothing you can't do with children's theatre," says Kenny. "Children think it's crazy if an actor is pretending not to be in the same room as them, and you know that children are not going to be polite about it. It's exhilarating."

7 December to 13 January (0113-213 7700; www.wyp.org.uk)