Half Twin (2006)

A rich girl Lok Yan (Candy Lo) and her fiance Ko Fung (Carl Ng) come to Hong Kong to meet Yan's poor elder twin sister Lok Ling (also starring by (Candy Lo). The twins haven't seen each other for 20 years. Ko Fung incites Ling, a simple-minded and hot-tempered girl, to kill Yan to obtain her status, wealth and security. As Ling has been unhappy about her fate over the past years, she yields to the temptation and killed Yan. But afterwards, Ling lives under great pressure and is losing control of herself. She is suffering from schizophrenia. Now, she only has half a soul!