Two authors are launching a High Court action against the publishers of The Da Vinci Code, which they say infringes upon their ideas.
The Da Vinci Code has made author Dan Brown a household name
Michael Baigent and Richard Leigh are suing Random House, claiming the bestseller lifts from their 1982 book The Holy Blood and the Holy Grail.
A High Court hearing will be held next week, followed by a trial next year.
Random House was unavailable for comment on the claim that Brown stole the idea that Jesus had a child.
A spokeswoman for Baigent and Leigh said the authors had been struck by alleged similarities to their history book.
She said: "The basis of their case is theft of intellectual property.
"There are huge chunks of The Da Vinci Code which they say is lifted from their book."
The Holy Blood and the Holy Grail was recently reissued through Century, part of the Random House group.
It features "cryptically coded parchments, secret societies, the Knights Templar" and links them to "a dynasty of obscure French kings" and the Holy Grail.
It also claims that Jesus and Mary Magdalene married and had a child together.
The Da Vinci Code, derided by critics and the subject of furious religious debate, won best book at this year's British Book Awards.
The novel sees an art historian follow a trail of codes and puzzles to explore claims that Jesus and Mary's bloodline survives to this day.
Audrey Tautou will co-star in the film, due out next year
A film is being made by director Ron Howard and starring Tom Hanks.
Baigent and Leigh wrote their book with a third author, Henry Lincoln, who is not taking part in the legal action due to ill-health.
In August, Brown won a court ruling in New York against writer Lewis Perdue, who claimed The Da Vinci Code plagiarised elements of two of his novels, Daughter of God, published in 2000 and 1983's The Da Vinci Legacy.
Perdue sought to block future distribution of the book and forthcoming film, as well as $150m (£84m) in damages, but the judge said any similarity was based on "unprotectable ideas".