The Gentle Madness.

Mothers often go to extremes and make sacrifices for their children, including feigning madness. Fun-nei's mother has been kept in custody in a mental hospital for killing her husband, leaving daughters Fun-nei and Si-ling on their own. Fun-nei later achieves success by making her eventful life story into a documentary. One day the mother escapes from the hospital and returns home. Furious that Si-ling has not reported the escape, Fun-nei clashes with her sister and films the conflict, eventually unveiling the hidden truth.