The fourth "Bourne" movie, "Untitled Bourne 4 Project", may be based on one of Robert Ludlum's books after all, but not from the "Bourne" series. When asked by Coming Soon during an interview for "The Curious Case of Benjamin Button" about the potential source material for "Bourne 4", producer Frank Marshall mentioned Ludlum's "The Parsifal Mosaic" saying, "Actually, there is. 'The Parsifal Mosaic' is one that we like."
Though not one of the "Bourne" series, "The Parsifal Mosiac" tells the story of a U.S. spy who falls in love with another spy who is revealed to be a double agent just before her death. However, when the U.S. spy retires from the spy business, he learns that she may still be alive and sets out to learn the truth.
On December 7 occasion, the film producer also slammed the speculation that the movie will be adapted from "The Bourne Betrayal". "No, the 'Bourne Betrayal' was written by a friend of Ludlum's... It had nothing to do with us," he explained about the decision for not choosing the new book as potential source. "We want to stay true to the original character."
Additionally, Marshall also confirmed that Matt Damon has yet to be signed on. "No, the only people signed on right now is George Nolfi, the writer, and me. We have to get a good script and then, hopefully, Matt will follow." Asked about the title he has in mind, he joked, "Well, there's a lot of jokes. 'Bourne Again,' 'Bourne Yesterday,' 'Bourne Free,' 'Bourne on the Fourth.' I actually want to do that. Call it that and release the movie on the fourth."