It been a very long time since I played it, but IIRC it's about a cartoonist who can't sell his creation (Flux Wildly, picture related) to a studio so he has to work on a show he hates. Then he ends up in the cartoon world where he has to help Flux save the world before shitty cartoons corrupt everything. Shenanigans ensue as expected.
The story and characters are kind of basic but they work pretty well, and it has some decent jokes as well. The main novelty of the game is that the main character is a live-action Christopher Lloyd in an otherwise cartoony world, giving the whole thing a sort of reverse Roger Rabbit vibe.