In the NYTimes Book Review, Laura Miller debunks the “fact” of the Priory of Sion

The ever-rising tide of sales of ”The Da Vinci Code” has lifted some pretty odd boats, and none odder than the dodgy yet magisterial ”Holy Blood, Holy Grail,” by Michael Baigent, Richard Leigh and Henry Lincoln. A best seller in the 1980’s, ”Grail” is climbing the paperback charts again on the strength of its relationship to Dan Brown’s thriller (which has, in turn, inspired a crop of new nonfiction books coming out this spring, from ”Breaking the Da Vinci Code” to ”Secrets of the Code: The Unauthorized Guide to the Mysteries Behind The Da Vinci Code”). ”The Da Vinci Code” is one long chase scene in which the main characters flee a sinister Parisian policeman and an albino monk assassin, but its rudimentary suspense alone couldn’t have made it a hit. At regular intervals, the book brings its pell-mell plot to a screeching halt and emits a pellet of information concerning a centuries-old conspiracy that purports to have preserved a tremendous secret about the roots of Christianity itself. This ”nonfiction” material gives ”The Da Vinci Code” its frisson of authenticity, and it’s lifted from ”Holy Blood, Holy Grail,” one of the all-time great works of pop pseudohistory. But what seems increasingly clear (to cop a favorite phrase from the authors of ”Grail”) is that ”The Da Vinci Code,” like ”Holy Blood, Holy Grail,” is based on a notorious hoax.