how does stevenson creates fear and mystery in Dr jekyll and Mr Hyde?

Mystery begins in the first chapter. The mysterious Hyde is discussed with really no sense of closure. This issue also arises in the matter of physical appearances, particularly architecture. In the first chapter, we learn that Hyde's mysterious dwelling is run down, neglected, and shabby. In contrast, Jekyll's home is extremely well kept, majestic, rich, and beautiful. Ironically, we eventually learn that the mysterious door is in fact connected to Jekyll's home, albeit a back entrance rarely used. Thus, it becomes clear that although idyllic to the public, even Jekyll's home, parallel to his personality, has a neglected, shabby, and perhaps dangerous portion hidden from view.