Gothic Mystery Books are a genre of literature that combines elements of both horror and mystery, typically set against the backdrop of a haunting, often old-world setting. These stories, which primarily target adult readers, are characterized by their atmospheric, chilling narratives that delve into the human psyche, creating an eerie blend of suspense, dread, and uncertainty. As a sub-genre of cozy mystery books, they maintain an element of comfort and familiarity, despite their ominous undertones.