It is true that filmmakers get mellower as they get older. It's the only reason to explain how Herman Yau could go from The Untold Story and The Ebola Syndrome to this rather tame thriller. Fortunately, he's become a better director, cuz this is better than his earlier Cat. III fare.
Andy Hui plays a cop that goes into a coma after a shootout with some thieves. When he awakens two years later, he is suddenly able to see ghosts. Turns out, this comes in handy, because a nurse rapist/murderer has been on the loose while he was asleep, and ghosts of the victims like to report themselves missing (?!?). Only in Hong Kong...
For a movie that's got some really wacky crap going on, this isn't that bad. There are some nice touches here: the ghosts that help with the investigation, and the clever way that Hui communicates with them (so as not to seem like he's talking to himself); the cheap scares of having gross ghosts just pop out of nowhere; the hospital ghost taunting the oblivious killer. But there's also some silliness: the out-of-left-field identity of the killer (although there is a clever red herring scene before they catch him); the badly translated transition title cards that make it seem as though the movie is going backwards; the ridiculous, yet somehow, appropriate ending. And, to show that the influence of Ring has reached the Chinese mainland, there is a ghost that, of course, looks just like Sadako. All and all, a surprisingly enjoyable movie; better than some of the supposedly "better" Japanese horror movies that everyone (me included) loves so much.