Two British authors accuse "The Da Vinci Code" mastermind Dan Brown of lifting the central theme for his perennial bestseller from their 1982 nonfiction tome, "The Holy Blood and the Holy Grail."

Dan Brown investigates the mystery of Holy Grail following the series of clues left behind by Jacques Sauniere, the murdered curator. Sauniere raised his granddaughter (Audrey Tautou), coaching her in endless puzzles. As an adult she became a cryptographer. When presented with the numbers in a scrambled form, she recognizes the sequence, and understands that it is part of a message. No spoilers included.

"The Da Vinci Code" also deals with Priory of Sion, a secret society formed in 1099, Knights Templar, and Free Masons.

Michael Baigent and Richard Leigh seek an injunction to prevent further use of their material, which technically could lead to a delay in the hugely anticipated debut of "The Da Vinci Code" film.

Although Dan Brown had admitted to using "Holy Blood" as one of many historical sources, he claims the book was not "crucial or important" to his main ideas. He furthermore disagrees with Baigent and Leigh's idea that Jesus was not crucified and instead went to live in France.

"This is not an idea that I would ever have found appealing," Brown told reporters outside the courtroom.

"Suggesting a married Jesus is one thing, but questioning the resurrection undermines the very heart of Christian belief."

This is not the first time "The Da Vinci Code" has been questioned over the copyright infringement. In 2005 a New York judge ruled that Brown's book did not plagiarize two books by Lewis Perdue, "Daughter of God" and "The Da Vinci Legacy." Perdue had sought $150 million and asked the court to block the release of the film.

"The Da Vinci Code" is directed by acclaimed director Ron Howard starring Tom Hanks, Jean Reno and Audrey Tautou, more famous as Amelie.

"The Da Vinci Code" is scheduled to open the Cannes Film Festival May 17 and go into wide release two days later.

However, Sony Pictures assures that the movie will launch on time. "This lawsuit is not about the movie and we are proceeding with our plans," Jim Kelly, senior VP of corporate communications at Sony Pictures Entertainment, told the Associated Press.

"The Da Vinci Code" and "The Holy Blood and the Holy Grail" share the idea that Jesus was married to Mary Magdalene and they had a child.

So are two thousand-plus other non-fictional books, Internet blogs, various forum posts, serious and not-so articles investigating the mystery of Holy Grail.

"The Da Vinci Code" even has a character named Sir Leigh Teabing, which as the British press points out, is an anagram of Baigent and Leigh.

Now, that's a puzzle!

No wonder many fans consider the court hearing another way to raise publicity around the movie's upcoming release.

The Da Vinci Code's plot has already caused controversy among the religious community. The Westminster Abbey refused to allow the production into the cathedral, and the movie was shot in a less famous church outside London. 

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