The Adventure of the Sussex Vampire: Sherlock Holmes

'The Adventure of the Sussex Vampire', written by British author Arthur Conan Doyle, is one of 12 Sherlock Holmes stories collected between 1921 and 1927 as The Case-Book of Sherlock Holmes. It was first published in the January 1924 issues of The Strand Magazine in London and Hearst's International Magazine in New York.
Holmes receives an odd letter that makes reference to vampires. Mr. Robert Ferguson, who comes to 221B Baker Street the next morning, has become convinced that his Peruvian second wife has been sucking their baby son's blood. By his first wife, he has a 15-year-old son named Jack, who suffered an unfortunate accident as a child and now, although he can still walk, he does not have the full use of his legs. After the bloodsucking began, Jack has unaccountably been struck twice by his stepmother, although Mr. Ferguson cannot imagine why. Ever since being found out by her husband, she has locked herself in her room and refused to come out. Only her Peruvian maid, Dolores, is allowed in. She takes Mrs. Ferguson her meals.