So the book I’m looking for was a fantasy book meant for younger/teen children. It was half novel/ half comic book. The little girl and brother share a love for a fantasy movie/world/game (I don’t remember) so her and her brother go to the local carnival and they go through the tunnel of love except he goes missing on the ride and she has to go to this fantasy world to find him (there was multiple books in the series but I only ever read book one)
Lost Classics of Teen Lit: Name That Book! 