Audrey Tautou and Tom Hanks in a moment from The Da Vinci Code

The Da Vinci Code ?is not a reinvention of the novel?. After all, author Dan Brown?s controversial, conspiracy-minded religious thriller has become a global industry ? the book has already sold 50 million hardback copies, with close to five million paperback sales in the UK so far. It has inspired reverential bus tours, been denounced by the Vatican and, most recently, been the subject of a high-profile court case.

But the court case is only one of the obstacles the film has had to overcome. Huge pressure was exerted on Sony, the studio making the film, from religious groups who wanted the film to differ from the novel, particularly in its inflammatory theory that for 2,000 years the Catholic Church has been covering up the fact that Christ was married to Mary Magdalene and fathered a daughter, whose bloodline has survived into present-day Europe.

Director Ron Howard has made it plain the film closely follows the book. His goal, he says, was to duplicate the experience of reading the book. Certain things have been omitted, although nothing major has been changed. ?We used the novel as the basis for our movie,? says Howard, ?and it is not a reinvention of the novel. It?s a screen adaptation of The Da Vinci Code.?

Howard, himself a fan of the book, had no intention of changing the storyline. ?I?m very interested in the range of themes,? he said. ?It?s intriguing on a lot of levels. It?s the kind of fiction that provokes thought and conversation and debate, and it did that for me when I read it. It?s quite unusual for a story to have that many ideas working in the same plot line, and I chose to make the film because I was intrigued by those ideas.?

For inspiration, Howard watched classic thrillers with spiritual elements, such as The Exorcist and Rosemary?s Baby. He is once again working with his longtime producer Brian Grazer, with whom he made Apollo 13, A Beautiful Mind, Ransom and Cinderella Man among others. Between them, their films have grossed billions of pounds and collected nine Oscars.

Tom Hanks, who previously worked with Howard and Grazer on Apollo 13 and the romantic comedy Splash, stars as Robert Langdon, the Harvard ?symbology? professor who becomes embroiled in a murder mystery of biblical proportions.

The French actress Audrey Tautou was chosen as his co-star over three Oscar-winning actresses who reportedly lobbied mightily for the role. The cast also includes Ian McKellen as Sir Leigh Teabing, the former royal historian whose life?s passion is the Holy Grail; Alfred Molina as Bishop Manuel Aringarosa, the president-general of Opus Dei; Jean Reno as the deeply religious police captain Bezu Fache; and Paul Bettany as Silas, the murderous, self-flagellating albino Opus Dei monk.

The filmmakers were refused permission to shoot in Westminster Abbey; but Lincoln and Winchester cathedrals co-operated, as did the Temple Church in London and Rosslyn Chapel in Roslin, Scotland. As for doubts about whether the film could be shot in the Louvre, these were resolved only when French President Jacques Chirac personally gave his stamp of approval. Even so, the Mona Lisa, which plays a key role in the story?s opening, was ruled off-limits and the film had to use a replica.

Howard and his crew shot for a week of nights in July, although conditions were less than ideal. ?We had to be very specific about every single shot we were going to do, both for security and for preservation reasons,? said Howard.

?There were all kinds of things we couldn?t do. In the script, there is blood on the floor but we couldn?t do that, and obviously we couldn?t take paintings off the walls.? The crew was also forbidden to shine direct light on the paintings.

The Da Vinci Code opens on May 19.