The creature in the garage

Trevor Nunn's new play Skellig is the result of a long car journey that left him and his family spellbound

The idea to adapt David Almond's Whitbread-winning children's novel Skellig for the stage came to the director Trevor Nunn on a long car journey.

"My wife and daughter were listening to the audio tape, and nobody moved - we were so riveted and in such an emotional state," says the former director of the National Theatre and the Royal Shakespeare Company. "And when we arrived back home, there were 13 pages of the book to go. We just sat in the car until the end."

But what was it that hooked Nunn and his family? "It is about belief," says Nunn. "The relationship with this creature, the Skellig, ultimately brings happiness to the boy and his family in a cynical adult world."

Skellig was David Almond's first novel, published in 1988. The tale of a young boy, Michael, who finds a creature, the Skellig, in a derelict garage is in the great tradition of children's stories that have a spiritual or religious subtext, such as The Lion, the Witch and the Wardrobe, The Lord of the Rings and even ET.

After meeting in 1999, Nunn and Almond set about putting on a workshop at the National. "We had a thrilling time and used enough of the text to make a small show," Nunn recalls. "But I said to the author that although we had found the right approach for a play, it needed a rewrite." Almond duly set to work on the adaptation.

Almond's children's play Wild Boy, Wild Girl toured the UK in 2001, and a stage adaptation of his Secret Heart ran at the Royal Exchange Theatre in Manchester in 2002. His other novels include Kit's Wilderness, Heaven Eyes and, most recently, The Fire Eaters.

Nunn, meanwhile, used a less conventional story-theatre technique for the play in order to include everything that happens in the book, and there will be a fly rig set up on stage to allow the cast to float through the air. "Yes, this is a very different project for me - not in scale, but in content," Nunn says. "We surround the audience and involve them. It is the actors' imaginations that bring things. It is very improvisational, and the company must really trust and rely on one another to make it work. That is why the company has become very close."

At the centre of it all is the mysterious Skellig, acted by David Threlfall, who played Smike in Nunn's production of Nicholas Nickleby and has recently been in Lindsay Posner's Tartuffe at the National Theatre. The play is designed by John Napier, who has collaborated with Nunn many times and has won numerous awards, including an Olivier, a Bafta and five Tonys. The music was composed by Shaun Davey.

But the exact nature of the Skellig remains a secret in the play. "I remember reading the blurb to the book and noticing that it tried very hard not to give it away," says Nunn. "I must go on in that vein."

The Young Vic, London SE1 (020-7928 6363; www.youngvic.org) to 31 January