Troublesome Night 17

Gay has been arrested for possessing drugs and is sent to prison. When Mrs. Lung visits him, she realizes that a demon is following him around, and sends Yan into the prison to help Gay. With the help of the warden, they discover the demon is a vengeful ghost of a woman whose husband was wrongfully imprisoned there, and committed suicide. All she wants to see is his grave, which should be behind the prison. (imdb)