The Resident Patient

In "The Resident Patient" by Arthur Conan Doyle, Sherlock Holmes and Dr. Watson investigate the strange case of Dr. Percy Trevelyan, a physician with a peculiar financial arrangement. His benefactor, Blessington, insists on living in his practice but becomes increasingly paranoid. When Blessington is found dead under mysterious circumstances, Holmes unravels a sinister plot tied to a criminal past.