Infernal Affairs is a series of three crime-action films directed by Andrew Lau and Alan Mak, starring Andy Lau and Tony Leung. It tells the story of a police officer who infiltrates the triads, and a police officer secretly working for the same gang. The Chinese title means "the non-stop way", a reference to Avici, the lowest level of hell in Buddhism. The English title is a word play combining the law enforcement term "internal affairs" with the adjective 'infernal'.