The undercover in Undercover Superstar was played by Guo Weiliang. Guo Weiliang is a martial arts star, but as a matter of fact, he hasn't been in battle in person for a long time, and he always uses body double when he encounters dangerous actions in shooting. So for more than 20 years, he has never won the best actor. In the plot of Undercover Superstar, Zhu Tie, a private detective who makes a living by secretly photographing celebrities' gossip, accidentally becomes the undercover of the Hong Kong police. Guo Weiliang, who plays an undercover supporting role in Gypsum, is sent to the new film crew of Kung Fu superstar Yuan Bao to investigate a case involving drug manufacturing and trafficking.