Your heroine just found out that one of her parents is a serial killer. Which parent? How does she find out? Where is she when she finds out? How does she react or feel about learning this? For example, maybe she’s okay with it because it explains so much of her own personality. Or maybe she’s horrified and tries to balance the scales by becoming a vigilante. Who is her romantic interest in this story and how do they meet? This could easily be a number of different genres from romantic comedy to a horror or suspense.