The Parasite is a classic work by Sir Arthur Conan Doyle is a fascinating story about the potential danger of mesmerism, penned before anyone knew much about hypnosis. The main character is a young man known as Austin Gilroy. He studies physiology and knows a professor who is studying the occult. The young man is introduced to a middle-aged woman known as Miss Penclosa, who has a crippled leg and psychic powers. She is a friend of the Professor's wife. The skeptical Gilroy's fiancée, Agatha, is put into a trance to prove Miss Penclosa's powers. This succeeds and Gilroy begins to go to the Professor's house where Miss Penclosa practices her powers on him . This is so Gilroy can look at the physical part of the powers.