Andy Tai as Lam Kong, Chief Inspector of Yau Tsim District's Anti Triad Squad
Roger Kwok as Cheung Kwok-fung, the main protagonist of the series, Senior Inspector of Team 1 of Yau Tsim District's Anti Triad Squad. He is Cheng Wai-ling's ex-husband and he adopts her son Chi-him after she dies in a traffic accident with her boyfriend John. Fung is good friends with fellow police officers Chow Ka-wing, an inspector of Yau Tsim District's Organised Crime and Triad Bureau, and Chan Chau, a sergeant of Tsim Sha Tsui's Criminal Investigation Bureau. He is also friends with Leung Yiu-ting, a former triad leader whom he arrested while working as an undercover cop in the past. Fung later develops a relationship with and becomes the boyfriend of his subordinate Chin Nga-lai.
Fennie Yuen as Chin Ngai-lai, a sergeant of Team 1 of the Yau Tsim District Anti Triad Squad. She is good friends with fellow police officers Jackie Wong, a staff member of the Tsim Sha TsuiPolice Station and Hui Sze-wing, a uniformed police constable. She is Chow Ka-wing's ex-girlfriend and later develops a relationship with and becomes the girlfriend of her superior Cheung Kwok-fung.
Dickson Lee as Chow Yuk-piu, an officer of Team 1 and Cheung Kwok-fung's subordinate.
Chan Wing-chun as Chan Tat-fei, an officer of Team 1 and Cheung Kwok-fung's subordinate.
Jerry Koo as Cheung Ka-keung, an officer of Team 1 and Cheung Kwok-fung's subordinate.
Deno Cheung as Choi Kan, an officer of Team 1 and Cheung Kwok-fung's subordinate.
The Chow family
Bowie Wu as Chow Kai-cheung, Tong Suk-yin's husband and Chow Ka-wing's father
Rainbow Ching as Tong Suk-yin, Chow Kai-cheung's wife and Chow Ka-wing's mother.
Nick Cheung as Chow Ka-wing, Inspector of Yau Tsim District's Organised Crime and Triad Bureau and the son of Chow Kai-cheung and Tong Suk-yin, He is good friends with fellow police officers Cheung Kwok-fung and Chan Chau and the ex-boyfriend of Chin Nga-lai.
The Chan family
Lai Huen as Yeung Nin, Chan Chau's mother.
Benz Hui as Chan Chau, Sergeant of Tsim Sha Tsui's Criminal Investigation Bureau and Yeung Nin's son. He was an old classmate and ex-boyfriend of fellow police officer Liu Sau-chu, Assistant Commander and Chief Inspector of Tsim Sha TsuiPolice Headquarters, and also good friends with fellow police officers Cheung Kwok-fung and Chow Ka-wing. Chau often bickers with Chu Yuen-yan but later develops feelings for her.
Camy Ding as Chan Chun, Chau's younger sister.
Wong Fung-king as Chan Ha, Chau and Chun's younger sister.
Shally Tsang as Chan Tung, Chau, Chun and Ha's younger sister.
The Fong family
Kwok Tak-sun as Fong Lik-sang, Liu Sau-chu's husband and Fong Yuk-ying's father
Lo Koon-lan as Liu Sau-chu, Assistant Commander and Chief Inspector of Tsim Sha Tsui Police Headquarters. She is the wife of Fong Lik-sang and mother of Fong Yuk-ying. Chu was the old classmate and ex-girlfriend of fellow police officer Chan Chau.
Karen Lee as Fong Yuk-ying, Fong Lik-sang and Liu Sau-chu's daughter.
The Leung family
Felix Lok as Leung Yiu-ting, a triad leader who was arrested by Cheung Kwok-fung during the latter's undercover mission. He befriends Fung after he is released from prison.
Alice Lau as Ma Wai-lan, a bar owner who is Leung Yiu-ting's wife and a good friend of Cheung Kwok-fung.
Police
Halina Tam as Jackie Wong, a staff member the Tsim Sha Tsui Police Station and good friends with fellow police officers Chin Ngai-lai and Hui Sze-wing. She is also the girlfriend of uniformed police constable Lee Wai-ming.
Hawick Lau as Lee Wai-ming, a uniformed police constable who is Jackie Wong's boyfriend and good friends with Hui Sze-wing as Chiu Chi-ho.
Natalie Ng as Hui Sze-wing, a uniformed police constable who is Chiu Chi-ho's girlfriend and good friends with Chin Nga-lai, Jackie Wong and Lee Wai-ming.
Micky Chu as Chiu Chi-ho, a uniformed police constable who is later promoted to sergeant, and promoted to inspector in the end. He is Hui Sze-wing's boyfriend and Lee Wai-ming's good friend.
Other cast
Joe Ma as John, Cheng Wai-ling's boyfriend and Cheung Chi-him's father. He dies with his girlfriend in a traffic accident.
Sonija Kwok as Cheng Wai-ing, Cheung Kwok-fung's ex-wife and Cheung Chi-him's mother. She dies in a traffic accident with her boyfriend John.
Chan King-kwan as Cheung Chi-him, the orphaned son of John and Cheng Wai-ling who is adopted by Cheung Kwok-fung after the death of his parents.
Celine Ma as Chu Yuen-yan, Chan Chau's bickering rival turned girlfriend.
Wilson Tsui as Mad Chiu, a vulgar triad member.
Yu Chi-ming as Yeung Wing-cheung, a triad leader who died from a car crash.
Lee Wai-kei as Sai-hing, a triad leader and Leung Yiu-ting's former underling.
