Inspired by Brian De Palma’s The Untouchables (1987), Kirk Wong’s gritty Hong Kong action thriller follows police officer, Ding Chun (Tony Leung Ka-fai), in 1930s Shanghai. With corruption rife throughout the force, he reunites with three wartime comrades to form a special drug task force, determined to wipe out the opium cartels that control the city, and the corrupt cops who protect them.