Carpenter's Gothic

This story has reeled me in but it still is confusing to me. I feel as if this book is written as a play rather than a story. I am able to follow the dialogue but only if I reread a few parts. The most interesting thing about this story is the relationship Liz, Billy and Paul share. It seems like they're all tied together because of Liz and Billy's father and if it weren't for him I feel maybe they'd really not speak with each other. Could Paul just have never liked Liz but instead just wanted the money. From what I could gather is Liz and Billy's father had a ton of money but his two children don't see any of it. Paul seems to be money hungry and is coming up with a scheme as to how to get money. Even going for a lawsuit because his wife was in a plane crash a few years prior.