German writer-director Philipp Stolzl is famous for music videos for such talents as Madonna, Mick Jagger and German metal band Rammstein, and he directed the video for James Bond theme song The World Is Not Enough.

Yes, he acknowledges, he has worked with difficult and temperamental performers but none was as challenging as the star of his new movie, North Face (Nordwand): "The Eiger is a far bigger diva than all these superstars put together," he jokes.

Based on a true story, the 1936-set mountaineering drama follows a failed expedition up the north face of the Eiger mountain in the Swiss Alps. Stolzl was determined to make the film as authentic as possible.

That meant he and his crew braved the Eiger themselves. North Face, he stresses, is not intended as an action movie in the Cliffhanger or Vertical Limit mode, filled with explosions and helicopters. "Those movies don't get close to what mountaineering is about," explains Stolzl, a keen mountaineer.

When preparing North Face (sold internationally by Beta Cinema), Stolzl watched every mountaineering movie he could find. He and producer Boris Schonfelder even came to London to meet Kevin Macdonald, the director of Touching The Void, one of the few recent mountaineering movies they admired.

"We said, 'Can we invite you for lunch and can you tell us how you made Touching The Void'' We learned a lot. Obviously, his film was a documentary and he had to make his movie in a different way than we did, but we took a lot of his ideas and tried to adapt them."

The film is based on the biographies of Toni Kurz (Benno Furmann) and Andi Hinterstoisser (Florian Lukas), two brilliant young German climbers determined to scale the Eiger, but encountering tragedy.

In an attempt to broaden the film's appeal, Stolzl's screenplay introduces a love element. Luise (Johanna Wokalek), Kurz's former girlfriend, meets him by chance just before he begins his climb. Now a journalist, she has come to the Alps with her colleague Arau (Ulrich Tukur), a committed Nazi, to report on the ascent.

North Face had its world premiere in Locarno's Piazza Grande in front of an audience of 8,000. It will be released by Majestic Filmverleih on 350 prints in Germany later in the autumn. The Swiss and German response to the film in Locarno was largely enthusiastic. The challenge is whether international audiences who do not know anything about Kurz's story will be drawn in.

The writer-director has various other film projects in the pipeline, including a children's movie about a boy and a robot and a historic project about German writer Johann Wolfgang von Goethe. Neither is fully financed yet.

Delays are nothing new to the director: there was a long hiatus between his first feature, tragic-comedy Baby (2001) and North Face. "That was partly because I was busy with other stuff but partly because some projects didn't make it into production. I'm really hoping the next movie won't take so long."