Hu Bak was a gang leader in Hong Kong. In the Walled City of Kowloon, he and his thugs tried to beat up a monk who, unknown to Bak, was his brother Hu Cheung. The gang fled when the Sixth Doctor and Peri Brown rescued Cheung.
When the Doctor, Peri and Cheung found the Platinum Dragon, Bak and his gang ambushed them. The dragon absorbed Bak, both controlling him and being controlled by him. Cheung had to fight him, and when he defeated the dragon, Bak was freed. (PROSE: Exclave)