A bunch of HK kids and their teacher visit a remote island where they encounter an axe-wielding maniac.

Taiwanese director Wu creates some effective stalk n' slash sequences by off-kilter camerawork,good editing and effective use of (library) music. The special f/x is quite explicit (one guy is cut in half+several Tom Savini style beheadings) and the identity of the killer may actually come as a surprise.
The pic is not as technically impressive (or well-acted) as Leong Po Chih's similar THE ISLAND (1985),but for a low-budget slasher, WHO'S KILLER is pretty decent.