Gaiman does no wrong. You have a fantasy novel set in a world that's divided into two sections, in this case it's "London Below"--where the fantasy takes place--and "London Above"--where the world we all know is maintained. Gaiman follows the main characters, a regular "London Above" Scottish man, Richard, and Door, who is a Lady of the world below. They go on a quest to figure out what happened to Door's family. On their quest, they fight different monsters, make friends, find some friends are traitors, and eventually figure out that the thing that you most want perhaps isn't the thing that you really need. Overall, it's a wonderful fast read; very entertaining and insightful.