The police request Roy to aid them in tracking the murderer of Langham, found slain in his room at the Piermont Hotel. In looking over the scene of the crime, Roy finds an unset emerald on the floor. A peach bearing tooth-marks is also found by the criminologist. Roy's suspicion is directed toward Hawkins, a society man, who has the suite next to the murdered man's room. Searching the suspect's rooms, Roy finds a fob from which the stone is missing. The emerald fits the setting perfectly.