Each book has to have a good setting to fit the book. In a mystery book I think that the story's setting should be a little sad and scary. This makes the book more exiting and fun to read. The story should be gloomy all together, so I think that the setting has to fit that. If the story was happy than the setting should be to, but for action story the setting should be exiting, and there should be different settings if its a fast moving story. So as you can see, for each story you need a setting that goes well with the story.