Inspector Hanscon is fished out of the water by policemen in a Harbor Police Boat. Hanscon is missing his fingers, causing Ruth Ransom to investigate the death. Paul Patton follows Ruth to a museum in Chinatown. She sees an almond shape ring worn by The Mandarin, noting to herself that it resembles one worn by the inspector.
The mandarin informs her that it is an Ancient Jewel of Chang Dynasty. In disguise, Paul watches as the mandarin leads Ruth through a secret door. Patton becomes The Fox and follows the pair by finding the release for the door, where he smells smoke from an opium den.
Ruth confronts the mandarin about the fingerless corpses. The mandarin opens a trap door and Ruth falls into a pit of water with a ladder leading upward. The Fox tackles the mandarin and uses a rope to pull Miss Ransom out of the pit after warning her to not touch the ladder. The mandarin rushes at The Fox with a knife, but The Fox flips the mandarin into the pit.
Instinctively, the mandarin reaches for the ladder and triggers The Mandarin's Fiendish Device. The device snaps on the fingers of the mandarin and severs his fingers.