Chen Zilong (Donnie Yen), who has extraordinary skills and extraordinary moves, has been lurking in the underworld for many years. As the right-hand man of the boss Changmao Xiong (Zou Zhaolong), he is under tremendous pressure physically and mentally. In addition, the boss has become suspicious of him and threatened the life of Zilong's mother (Paw Hee Ching). He is eager to resume his job and quit the underworld. This time, Xiong sent Zilong to the mainland to investigate the true and false of the organization member Sunny Luo Zhiwei (Andy On). Sunny was born in Chinatown, USA. In his early years, he mixed with Zilong in the underworld, but gradually became bigger and secretly blackened Xiong's goods. On the other hand, Zilong's boss Zhang Sir (Ronald Cheng) also ordered Zilong to investigate Sunny in exchange for reinstatement. Who knew that the trip to the mainland was very dangerous. Sunny was cunning and vicious, and there were frequent conflicts and contradictions in cooperation with the mainland police. In addition, the mysterious assassin "Blade" (Zhang Hanyu) appeared from time to time, and Zilong unknowingly stepped into a vortex of conspiracy...