I need a creepy idea for a story, details inside, help!?

I'm doing a short story, that's going to be a picture book and the entire story is going to rhyme. I want an idea similar to things like Corpse Bride and Coraline. Just something that I can make a creepy cartoon, but that's fun/morbid to work with! I want the main character to be a girl named Imogen. Help!