Some challenges a filmmaker would have adapting this book into a movie would be that Dan Brown includes so many historical facts and information that it would be hard to convey those facts into a movie. Also, the characters are hard to create because of all the thought process Dan Brown includes in the book. Brown's writing style is so incredibly detailed yet fast paced; a combination you can't really make into a movie script.
Scenes to keep-
1. A scene that definitely needs to be kept is the scene where Fache takes Robert Langdon to see Sohpie's grandfather's body in the Louvre. This needs to be kept because it gets the plot rolling and causes the story to pick up pace dramatically.
2. Another scene that needs to be kept is the scene when Robert and Sophie are extracted from the Swiss Bank by the manager because he wants to protect Sophie's grandfather's private possession that she had withdrawn from the vault. This needs to be kept because it starts several plot twists from this one simple act.
3. One other scene that needs to be kept is the seen when Sophie and Robert are inside the art gallery where the Mona Lisa is kept. Not only is this essential to the plot line, it also includes several interesting facts that would keep the viewer engaged.
Scenes to discard-
1. One scene that isn't needed is the scene of the bishop on the plane to Paris. I feel this would really slow down all the intensity because it was thrown in the middle of some intense scene to act as a bridge. You can't do those kinds of scenes in movies.
2. Another scene that could be cut is when the nun makes the phone call to the four people in the Priory of Sion. This isn't needed because you learn of their deaths later on and it just becomes repeated information.
3. One other scene I would get rid of is when Sophie and Langdon pull off to the side of the rode in the armored truck they stole from the bank. This slows down the intensity of the current situation and really isn't important in anyway.