Holmes receives two odd letters that make reference to vampires. Mr. Robert Ferguson, who comes to 221B Baker Street the next morning, has become convinced that his Peruvian wife has been sucking their baby son's blood. Several times, she has been caught doing this by the nurse, who at first hesitates to tell Mr. Ferguson about it. Indeed, Mrs. Ferguson bribed her to keep quiet. First published in Strand Magazine and Hearst's International Magazine, January 1924.