A murder case has caused a big storm in the underworld. Chinese-American drama fanatic Zhang Xilun (played by Wang Haoxin) returned to Hong Kong to look for performance opportunities. By chance, he was entrusted with an important task by policewoman Gu Xinyi (played by Feng Yingying), asking him to pretend to be the orphan of the leader of the Four-United Gang. With the help of veteran undercover Gao Bin (played by Zhang Zhenlang), Xilun became the leader. Afterwards, Xilun repeatedly lent a helping hand to the underworld leader Su Zhishan (played by Tang Yi) and female star Zhuang Mingli (played by Gao Haining); the big sister of the nightclub Yao Qingshui (played by Jiang Jiamin) and three unrelated sisters also revolved around Xilun. Xilun had just entered the underworld and became the best partner with Gao Bin. With the desperate protection of the gold medal thug Lu Qiu (played by Zhu Minhan), they resolved many crises, but they didn't know that there was a shocking conspiracy waiting for him behind the society...