The Adventures of Sherlock Holmes "The Greek Interpreter"

A man named Melas is repeatedly hired as a Greek interpreter under mysterious and threatening circumstances, only to find himself trapped and used to communicate with a captive foreigner against his will. Holmes and Watson are drawn into the case partly through the involvement of Holmes's brother Mycroft, who makes a rare appearance and reveals his own impressive deductive abilities. The investigation uncovers a sinister scheme involving inheritance and imprisonment, placing both Melas and the captive in grave danger.