There are quite a few. 'The Strange Case of Dr. Jekyll and Mr. Hyde' by Robert Louis Stevenson is a classic mystery of the Victorian era. It delves into the duality of human nature, which is presented in a very mysterious way. The character of Mr. Hyde is shrouded in mystery, and the story keeps you guessing about what's really going on. Additionally, 'Martin Hewitt, Investigator' by Arthur Morrison is another example. It features a detective solving various mysteries in the Victorian setting, with detailed descriptions of the era's society and its problems.
One popular mystery Victorian era novel is 'The Moonstone' by Wilkie Collins. It is often considered one of the first detective novels in the English language. Another is 'Sherlock Holmes' stories by Arthur Conan Doyle. These stories feature the brilliant detective Sherlock Holmes and his loyal friend Dr. Watson, and they are full of intricate mysteries set in Victorian London.