This isn't the kind of second coming Dan Brown was hoping for.

Two authors who failed in their lawsuit alleging the Da Vinci Code author stole their ideas to form the basis of his mega-selling book have been cleared to appeal.

On Wednesday, London's Court of Appeal approved a lower court judge's decision to grant Michael Baigent and Richard Leigh the chance to challenge an April ruling dismissing their claims that Brown ripped off theories from their 1982 nonfiction tome, The Holy Blood and the Holy Grail.

The Da Vinci Code was given an extra boost this summer after it was turned into a Hollywood blockbuster directed by Ron Howard and starring Tom Hanks, Audrey Tautou, Jean Reno and Ian McKellen. The film has racked up nearly $730 million worldwide (and counting) to become one of the Top 25 highest grossing movies of all time.

In their book, Baigent and Leigh outline the so-called bloodline theory, asserting that Jesus married Mary Magdalene and together had a child, whose existence was covered up by the Catholic Church.

Brown was a defendant in the suit; instead Baigent and Leigh were in the unusual position of suing publisher Random House, which also released their book (known in the States as Holy Blood, Holy Grail). Still, Brown took the stand to defend his work, acknowledging that he read Holy Blood--and even paid tribute to the book by naming a key character after Baigent and Leigh--but insisted that he crafted the thriller on his own.

On Apr. 7, a High Court judge sided with Brown and declared that the rival authors had "failed" to prove their allegations. On the plus side, the high-profile legal tussle was great publicity for Baigent and Leigh whose work, after two decades collecting dust in relative obscurity, climbed the charts again to become one of Amazon.com's top sellers.

Speaking to the BBC, the authors' attorney said he believes the appeal has "a real prospect of success."

Then again, Brown has a solid track record in court.

Two weeks after Baigent and Leigh's initial defeat, the 2nd U.S. Court of Appeals upheld a federal judge's ruling that declared The Da Vinci Code did not violate the copyright of another writer. Lewis Perdue had claimed his books Daughter of God and The Da Vinci Legacy were the real basis for The Da Vinci Code and sued Brown fro $150 million. But the court said the ideas in Perdue's book were "unprotectable."

A hearing has not yet been scheduled for Baigent and Leigh's appeal, but one is likely to go forward either before the end of the year or in early 2007.