Everybody has a different idea of a closed setting. What I think of a closed setting is when something mysterious happens. Then a big clue comes right after it. Like for example in the book "The Hound of the Baskerville" Dr. Watson and Sherlock Holmes were talking when they heard a scream so frightening it shocked both of then. As they went out looking for were the scream came from they heard like a beast in the bushes. They found a dead body of a man. The dead man indeed was wearing Sir Henry's clothes. This gives us a big clue in the story that somebody is trying to kill Sir Henry Baskerville.