Sham Shui Po, there is the most famous red-light district in Hong Kong. Li owns a few of the apartments in the building and she earns a living by renting them out to the prostitutes. To the prostitutes though, she is more a friend than just a landlord. She gets together a group of prostitutes and work as hard as they could, trying to attract business to turn the tide. Still, they do not know they are quietly approaching death.
It begins with the missing of a prostitute Ping. Ping is one of the tenants who live with her young daughter. In the process of finding Ping, Li discovered there had been a lot of missing prostitutes in this building, yet none of them were found. The building was somehow isolated from the outside world and a massacre begins.
Li and the prostitutes have to find Ping and to fight a battle of wits with the invisible murderer. As more evident of the murderer’s identity revealed, a tragic truth hidden for over twenty years starts to unveil.