ByAriadne Barcelo, writer at Creators.co

5. The scope of the project is massive. A huge camp of trailers greeted me when I pulled up to the Tura Castle, outside Budapest. I was surprised by the number of people working this movie. Around 200 cast and crew members have a job for months, partly because I sat down one day in a little farmhouse in Winters, CA, with the strange notion that an angel might fall in love with a mortal girl.

4. The casting is perfect. I expected to feel some rift between the characters in the novel and the actors portraying them. But when they all walked toward me for the first time, I let myself imagine they were angels and demons. That wouldn't have been possible if they hadn't been cast so well.

3. Actors can step into The Zone more quickly than writers. I require an hour of very focused window-staring before I can start writing, but I learned my first night on set how deft actors are at slipping in and out of character. I was having a conversation with Joely Richardson about a book we'd both adored when director Scott Hicks called her to set. Joely straightened her spine, tightened her expression, and Miss Sophia stalked away from me.

2. Scenes take unexpected directions. When I sit down to write a scene, I have a plan in mind, and I'm thrilled when a character disregards my goals and takes the story to a place I hadn't imagined. On set, I saw that Scott Hicks welcomes this experience, too. He told me about a scene in which he thought the camera's focus would be on Joely (Miss Sophia). After they'd shot the scene, he saw that Lola Kirke (Penn) was "emotionally peaking." Scott shouted, "Roll!" just in time to capture an essential tear sliding down Penn's cheek, never meant to be in the movie.

1. There's a moment in the movie that would be wonderful in the book. Readers beg me not to let the movie stray from the book. I assure them that everyone working on the film agrees. But there is one new moment in the film that is so economical and so moving, it would have worked beautifully if it were in the novel. I hope my fans will think of this added scene like one of the "extra" chapters that accompany the Fallen books. I can't wait for you to experience all of it on the big screen.

I'D LOVE TO KNOW WHAT YOU GUYS THINK?