Robert Langdon has just given a lecture in Paris on symbolism when his book signing is interrupted by the police who take him to the Louvre. He is asked by Captain Fache (Reno) to give his opinion on the murder of the curator, who left some grisly clues. He is then tipped off by Sophie (Tautou) a cryptologist, who also happens to be the curator's granddaughter, that a further clue points to him. The pair escape into the Paris night, but not before uncovering several further clues in the Leonardo paintings which result in a key falling into their possession.

As the mysteries mount and keep on pointing back to the legend of the Holy Grail the pair of fugitives seek the help of a grail fanatic, and multi-millionaire, Sir Leigh Teabing (McKellen). With Silas (Bettany) the Opus Dei hit-man monk on their trail, all the parties must move swiftly to avoid the long arm of this fanatical branch of the church and the law. The clues are solved, one after the other, taking them on trail from Paris to London to Scotland.

That's a very concise version of events from this two and a half hour film (it took me five hours to read the book on a middle haul flight). Ron Howard knows that a large part of his audience will already know what is going to happen and to his credit he brings in some good CGI effects to show past historical events (the fall of Jerusalem, the suppression of the Knights Templar - pronounced "Templaaaar" by Hanks) and the way that Hanks pieces together some of the clues. Even Teabing gets to play with some nifty software as he demonstrates to Sophie ambiguities in Leonardo's Last Supper.

Brown's book is an excellent piece of fiction that combines myths with historical facts and half truths and has great slices of detection and thriller aspects woven in. So is the film a great thriller too? No. There is a reasonable car chase through Paris, and Bettany is chilling as the monk killing to order, but at times it falls a little flat and more than once there were titters in the audience when Hanks delivered some pretentious lines.

There is also a major flaw in the casting. At first I though that Hanks and Tautou would be a dream team, but in reality they are both bland beyond belief. With no chemistry between them at all, it is left to the supporting cast to carry the picture. This they do well. McKellen steals every scene with relish, and even Reno and Molina hit the spot, each portraying their own obsessions with finesse.

This isn't a bad film, it's just a slightly above average thriller that will be seen by countless millions due to the phenomenal book sales, and the free publicity with the clerics weighing in, a court case at the perfect time, and plenty of books discussing the themes found in Brown's best seller. A different main pairing and some tweaking with the script would have delivered something with a bit more edge, but all involved will make their bank managers happy whatever.