The terrorist organization "Waganbu" infiltrates Hong Kong and sets off a battle for chemical weapons in Hong Kong. The commander-in-chief of the Flying Tigers, Fan Shaofeng (played by Moses Chan), is ordered to lead the Flying Tigers to fight wits and courage with the terrorists. The Flying Tigers are trapped in the ruthless killing of Waganbu. Special Service Team Superintendent Zhan Bowen (played by Ma Dezhong) summons the elite police officers Zhang Weihua (played by Zhang Zhaohui), Zhang Jiaxuan (played by Huang Zongze) and Gao Zile (played by Ron Ng) to form a secret anti-terrorist team STeam. Faced with numerous crises, with the assistance of Interpol Xu Junfei (played by Michael Miu), the two generations of middle-aged and young people finally put aside their grudges and joined forces to prevent the spread of chemical weapons virus in Hong Kong.