Infernal Affairs III is a 2003 Hong Kong crime thriller film directed by Andrew Lau and Alan Mak. It is the third and final installment in the Infernal Affairs film series, and is both a sequel and a semi-prequel to the original film, as it intercuts events before and after the events in the first film. Andy Lau, Tony Leung, Kelly Chen, Anthony Wong, Eric Tsang, and Chapman To reprise their roles again, joined by new cast members Leon Lai and Chen Daoming.