"Bun, a schizophrenic, former police inspector comes out of retirement to help a rookie detective solve a complex murder case involving a missing colleague and a suspected policeman suffering from a multiple personality disorder."
Sean Lau
as Inspector Chan Kwai Bun
Andy On
as Inspector Ho Ka-on
Gordon Lam Ka-Tung
as Ko Chi Wai
Kelly Lin Hsi-Lei
as May Cheung
Karen Lee Choi-Ling
as Gigi
Joseph Lee Kwok-Lun
as Wong Kwok Chu
Eddie Cheung
as Violent Man - Ko's Inner Personality
Lam Suet
as Fatso - Ko's Inner Personality
Jay Lau Kam-Ling
as Calculating Woman - Ko's Inner Personality
Jeff Cheung Ka-Kit
as Ko's Inner Personality
Lu Ching-Ting
Chiu Chi-Shing
Hung Wai-Leung
Flora Chan Wai-Shan
as May Cheung in Bun's Eyes
Jonathan Lee Yat-Sing
as Weak Boy - Ho's Inner Personality
Jo Kok
as Schemy Woman - Ho's Inner Personality
Eddy Ko Hung
as The Chief
Yuen Ling-To
as Policeman
Jimmy Wong
as Restaurant Manager
Ronald Yan Mau-Keung
as Chi-Wai's Boss
Apple Chow Suk-Wai
as 7-11 Worker
Jackson Ha Chak-Shun
as Ko's Colleague
Jack Lai
Singh Hartihan Bitto
as Naresh Sharma
Wong Shiu-Keung
as Policeman (uncredited)
Lui Siu-Ming
as Mahjong Parlour's Staff (uncredited)
Mark Cheung Yiu-Fai
as Mahjong Parlour Customer (uncredited)
Soi Cheang
as Inspector Ho Ka-on (voice)
Florence Kwok Siu-Wan
as May Cheung (voice)
Peter Chan Bei-Dak
as Cameo (picture in police file)
Wai Ka-Fai
Director
Johnnie To
Unit Manager
Martin Richard Chappell
Sound Designer
Raymond Chan Kam-Ho
Production Design
Charles Heung
Executive Producer
Kuk Kok-Leung
Line Producer
Tina Baz
Editor
Producer
Au Kin-Yee
Screenplay
Art Direction
Stanley Cheung Sai-Kit
Costume Design
Cheng Siu-Keung
Director of Photography
Midco Chu Wai-Fong
Makeup Artist
Xavier Jamaux
Original Music Composer
Mark Garbarino