bad casting, directing and worst of all, the careless decision by using the every actor's original voice. how could it possible that the mother's tone and accent is pure mandarin Chinese, a northern dialect accent, while the son speaking in cantonese accented Chinese? unless this so-called undercover son is adopted by a hongkongness foster parents and later reunited with his real mother, we could never get used to such big difference of accents between mother and son. and then, this guy's superior officer, my, is such a bad cast, who not in the least like a pencil pusher high ranking police office but an accounting clerk. then, the other two gang-bangers' stereo types are so lame and so formulaic, no big difference from their other roles in so many similar genre movies. i just wish donnie yen and all the cast in this movie speaking pure cantonese that at least the whole movie might look more convincing. but the stupid production people decided to cast a fragile Chinese doll to be the case officer from the mainland china and forced a awkward and embarrassing romance between the hongkongness undercover and her, their scenes just looked so contrite and unnatural. the mother role was also a cast of totally unnecessary. the dialog is also so stupid and contrite. this movie in general is a disaster from the very beginning to the end, simply ruined by a stupid screenplay, wrong cast, wrong accents, wrong arrangements almost every thing. to me, giving this movie 3 stars is already over-rated.