Mystery Literature refers to a genre of fiction typically involving a mysterious death or a crime that needs to be solved. This category encompasses adult mystery books which are primarily written for adult audiences and often contain more complex themes or darker subject matter. Psychological mystery books, a sub-genre, delve deeper into the minds of characters, exploring motives and mental states, usually leading to unexpected plot twists. The term Mystery Books, which is broader, includes all types of books that are centered around a mystery, regardless of target audience or specific sub-genre.