Dan Brown is being sued for plagiarism by two different groups.
Look at this link for more details.
The books involved are, Holy blood Holy Grail by Michael Baigent, Richard Leigh and Henry Lincoln, published in 1983, and The Da Vinci Legacy By Lewis Perdue Originally Published 1983, Pinnacle Books
The Holy Blood Holy Grail uses the same research as The Da Vinci Code but states it as fact.
The Da Vinci Legacy is a novel with striking similarities to The Da Vinci Code
I will be going into more about The Da Vinci Code in subsequent posts