An undercover cop works to take down the Triads in Hong Kong. The movie is based on a popular video game of the same name.

Sleeping Dogs is set in a contemporary Hong Kong, which is split into four districts named after regions of the city. The game reveals the story of Wei Shen , a former San Francisco police officer who was transferred to the Hong Kong Police Force and assigned the task to infiltrate and destroy a Triad organization known as the Sun On Yee .The main storyline features two sub-plots: Shen's balance between completing his police mission whilst committing crimes to prove himself to the Triads, and missions assigned by a Triad lieutenant, including assassination of Triad members loyal to other lieutenants. Shen's mission is coordinated by Police Superintendent Thomas Pendrew , and progress made by Shen is reported to his handler, Raymond Mak. Shen infiltrates the Sun On Yee via his childhood friend Jackie Ma , a low-level Triad member; and his loyalty is tested by the Triad boss "Red Pole" Winston Chu . Other characters in the game include the head of the Sun On Yee, David Wai-Lin "Uncle" Po , Shen's love interest Amanda Cartwright , Winston's right-hand man, Conroy Wu , singer Vivienne Lu , and Shen's girlfriend Not Ping .