Sherlock Holmes - Book 34 - The Adventure of the Golden Pince-Nez
Summary
A young man working as the assistant to a professor has been murdered. While it appears that anyone could have entered the house and committed the murder, a clue in the form of a pair of gold glasses is found near the body. Working on the assumption that the killer wore the glasses as well as several other clues, Holmes comes to the chilling realization that the murderer is still in the house.