After the colossal success of The Lord of the Rings, it's interesting to watch New Line play it cautiously with two new potential fantasy trilogies. The first episodes in both trilogies are in production on neighboring soundstages at Shepperton Studios, near London's Heathrow Airport, when RT visits in February 2007. But executives will wait until they're both released before committing to make the next two films in each series.

And early indications following the release of the first film of the His Dark Materials series, based on Philip Pullman's trio of acclaimed parallel-world novels, suggests that decision will be a tough one to make. We're still waiting to hear if The Golden Compass, with its A-list cast including Nicole Kidman and Daniel Craig, will spawn a sequel, though indications are that it probably won't.

In the next soundstage over, director Iain Softley is taking a more grounded approach to Cornelia Funke's Inkheart trilogy about a family caught between the real world and the worlds created in various books, the third part of which hit bookshops last year. Instead of green screens, we walk into the Inkheart soundstage and find the massive interior of a ruined cathedral, with huge stone staircases leading up towards the high-arch of the ceiling structure, stretching several stories up above our heads. Along the left side is an entire village street, with shopfronts, electric wiring and stone buttresses. Much of these stones were brought back from Italy, where the exteriors were shot. This is the setting for the film's big final sequence, which is being kept tightly under wraps as it apparently diverges from the novel to some degree.

In another soundstage, there's the cavernous, torch-lit interior of a castle that houses the villainous Capricorn. The cast is in here, performing a scene in front of a blazing fireplace with an army of leather-clad henchmen hovering around the edges. Recently Oscar-crowned Helen Mirren is sitting patiently on a bench with her hands bound and her mouth gagged. Brendan Fraser is standing manfully in the middle, with his trademark floppy haircut and rising young star Eliza Bennett at his side. As Capricorn himself, Andy Serkis is facing him with a gleeful grimace, looking more than a little Dr. Evil-esque with that five o'clock shadow on his shaved head. And right on cue, Paul Bettany strides in with a long coat and wild hair to propel the scene forward.

They film Slate 73 three times, at which point Softley is happy. Bettany goes straight back to a conversation on his mobile. Serkis grabs another cup of coffee. Fraser retires to a director's chair in the corner and continues reading a novel. He's nearly at the end, and it clearly has him gripped.

It turns out that his passion for reading is the main reason Fraser was drawn to Inkheart. "One of the most important things about the book is that it's written to be read aloud," he says, "and I think it's about the possibility to connect with kids again. To read something aloud to a kid really means a lot. So the book advocates literacy, and to make it into a film will continue that trend."

Bettany admits that he's not normally a fan of the genre. "I was reading the book with my 9-year-old when the script turned up," he tells RT. "I usually find fantasy quite difficult, but I didn't when reading this, and I think that's because it's so firmly set in this world."

Serkis agrees: "It's rare to read a fantasy script that's firmly rooted in reality and yet can translate into a fantasy world. That was what was appealing about it." For the film, the duct tape-obsessed Capricorn has been both deepened and lightened up, making him more shaded and much wittier."