Nick Cheung as Jack Hui, King's childhood friend and an important witness of the selling of smuggled cigarettes bribery case.
Karena Lam as Kong Suet-yee an ICAC Investigator/Expert negotiator and estranged wife of Chan King-chi
Anita Yuen as Chung Ka-ling, a customs official charged with corruption.
Alex Fong, the ICAC Chief Investigator and supervisor of King and Shirley.
Deep Ng
Carlos Chan as Gary, an ICAC Investigator and subordinate of King.
Kathy Yuen as Chi-ching, an ICAC Investigator and subordinate of King.
Hugo Ng as Ko Ching-man, defense barrister.
Charlene Chang
Production
Development
The project was first announced to be in development in December 2017, with Alan Mak writing and directing, and his frequent collaborator Felix Chong serving as producer, and set to star Sean Lau, Nick Cheung and Karena Lam. Lau was cast as an ICAC investigator, Cheung as a widower who has also lost his daughter, and Lam as Lau's wife. On 19 March 2018, the film was promoted at the Hong Kong Filmart, where it was attended by director/writer Mak, producers Chong and Ronald Wong and cast members Lau, Cheung, Lam, Michelle Wai and Kathy Yuen. There, Mak also revealed that he developed several stories for the film and decided that Integrity would be the first installment of a planned trilogy.
Filming
Principal photography for Integrity began in April 2018. On 11 April, a scene was filmed in a restaurant in Central, Hong Kong where Lau confronts Anita Yuen, who guest stars as an corrupt customs director. On 24 April, filming was carried out indoors with cast members Lau, Cheung, Alex Fong, Carlos Chan and Kathy Yuen, while Albert Yeung, head of Emperor Motion Pictures, also visited the set. There, Lau also revealed that director Mak helped him prepare for his role as an ICAC investigator by giving him research information and introducing him to former ICAC agents. Production for Integrity officially ended on 24 July 2018, with a wrap-up ceremony attended by the cast and crew. Aside from Hong Kong, filming also took place on location in Australia.
Box office
Opening on 5 February2019 in Hong Kong, Integrity played to blockbuster business, with showings at multiple cinemas being sold out. The film grossed HK$3.5 million on its opening day, making it the highest single day gross of the day. On the second day of release, the film has reached a gross of HK$8 million and had quickly passed the HK$10 million mark by its third day of release. A day later, the film hs reached a gross of HK$15.05 million. Shortly after, the film has also managed to pass the HK$20 million mark by its sixth day of release which was also the beginning of its second week of release. By 14 February, the film has reached a gross of HK$23 million. By the end of its second weekend, the film has accumulated a total gross of HK$28,078,348. During its third week of release on 19 February, the film has passed its HK$30 million mark, making it the box office champion among local films during the Chinese New Year holiday period. Integrity has grossed a total of HK$31,253,306 at the Hong Kong box office and is currently the highest-grossing domestic film and the fourth-highest-grossing overall film of 2019 in the territory.
