Adaptation.
Boy, to be a fly on the wall for this movie pitch. A fictional movie about the inside of a real writer's head that's writing a half-real screenplay about a real book based upon real characters. This movie works on all those levels with amazing and surprising intersections between the layers. This is one of the most creative screenplays I've ever seen. It's just so funny and clever and recursive, especially how it handles the "second part" of the movie (I don't think it's a spoiler to call it hilarious satire). I didn't even know while I was watching that "The Orchid Thief" was a real book based on real characters ... and it blows me away that Charlie and Donald Kaufman were both nominated for "Best Writing, Screenplay Based on Material Previously Produced or Published", which must have been quite an interesting decision for the Academy. A masterpiece.