Mad Detective (Chinese: 神探) is a 2007 Hong Kong psychological thriller film produced and directed by Johnnie To and Wai Ka-Fai. Mad Detective was first screened at the 64th Venice International Film Festival, and later premiered at the 2007 Toronto International Film Festival, before being released in Hong Kong on 29 November 2007. The film's screenplay won "Best Screenplay" awards at various Asian film ceremonies.