What is the exposition for Hound of the Baskervilles?

The exposition of "The Hound of the Baskervilles" introduces the eerie legend of the Baskerville family, particularly focusing on Sir Charles Baskerville's mysterious death, which is rumored to be linked to a supernatural hound. This sets the stage for Sherlock Holmes and Dr. John Watson, who are drawn into the investigation to uncover the truth behind the legend and the circumstances surrounding Sir Charles's demise. The story begins with a conversation between Holmes and Watson, establishing their detective partnership and the ominous atmosphere of the moorland surrounding Baskerville Hall.