Conspiracy (2000)

Maggie is having a bit of a relationship crisis after her boyfriend Andy returns to Hong Kong from a trip to Thailand. She spied Andy with new girl Sharon at the airport and he seems to have lost all sexual interest in her. Maggie's old habit of sleepwalking returns after ten years, just as Chiang - Andy's boss - is murdered. When she wakes up on another night with a kitchen knife in her hands, she begins to worry that she could be involved in some way. And then the sister of Sharon is also murdered