Forget Me Not (2010)

Lam Yee is a school teacher who cannot remember anything happened to her before 15 years old. Discovering her boyfriend has another another woman, Yee attempts to commit suicide, but gives up the idea when she meets a child wandering in the street. Suspecting the child may be one of the students in her school whose parents have suddenly died of a car accident, she takes care of the child as if he is disease. When traditional medical treatment fails to cure the child's sickness Yee brings the child to try a Chinese folk ritual called "soul-calling" - an evil expelling ceremony to cast out the demon that has scared away the child's soul. The ceremony unveils the true identity of the child which, to her surprise, is related to her mysterious past!