The Tong of the Black Scorpion was a 19th century Chinese cult devoted to the ancient god Weng-Chiang. The Fourth Doctor called it one of the most dangerous criminal political organisations on Earth.
The Tong's followers believed the god would one day return and rule the world. This seemed fulfilled when 51st century war criminal Magnus Greel travelled back in time to 19th century China and used his advanced technology to take control of the cult. In London the Tong searched for the time cabinet which Greel had originally used. It had come into the possession of Professor George Litefoot as a gift of the Emperor of China.
In London, they were responsible for the abduction of the young girls that Greel needed for his recovery, as well as building him a large, temple-like headquarters and performing crimes for him.
The Tong's agents had a black scorpion tattooed on one of their hands. When caught, they were expected to commit suicide by taking a pill containing highly concentrated scorpion venom. The leader of the cult, subordinate to Greel, was Li H'sen Chang, who worked in the Palace Theatre as a conjurer. (TV: The Talons of Weng-Chiang)
