Forest of Death(also known asSum yuen) is a 2007 Hong Kong horror film directed and co-written by Danny Pang .
Police detective Ha Chun-Chi ( Shu Qi ) is investigating a rape and murder that took place in a mysterious forest that has also been the scene of many suicides. The main suspect in the murder case is Patrick Wong ( Lawrence Chou ), but he denies committing the crime.
Ha's investigation leads her to botanist Shum Shu-Hoi ( Ekin Cheng ), who has been experimenting with plants from the forest. Shum's girlfriend, May ( Rain Li ), feigns interest in the forest to gain information for a tabloid television show she works for.
Shum's experiments reveal that the plants can act as witnesses in the murder case, and sets up a re-enactment of the crime in the forest, where the plants will act as lie detectors.