Suay Laak Sai (2007)

At a Thai hospital, a doctor and his seven nubile nurses engage in the sale of bodies. Jealousy causes Tawan, one of the nurses, to threaten to blow the whistle on the practice, so the others murder her. The dealer in bodies doesn't arrange for delivery of Tawan's corpse for a full week. As midnight approaches on the seventh day after the murder, each of the remaining nurses as well as Dr. Taa, faces a supernatural revenger. In flashbacks we see the events leading up to the murder and realize the full range of relationships among the main characters, including the duplicitous Dr. Taa and Tawan's sister, Nook.