When it's popular, you can be certain Jing Wong wants his piece of the pie. Even (or especially) when the material is quite dubious. Not quite sure why he ended up directing the fourth one in the series, but don't expect him to suddenly raise the bar. While it's easily the best film of the bunch, it's hardly worth bothering with.
The plot is as basic as can be. Daniel is an ex-CIA agent who got shafted because of his sexist behavior. He lives next to Kwan, an attractive writer. It doesn't take long before Daniel becomes infatuated with Kwan. Pretending to be a lawyer, he frees to convicts in order to help him out with his devious plan.
A dumb plot and cheap styling, what you do get here is a half-decent cast. Nick Cheung, Anthony Wong and a remarkable cameo from Yonfan are the highlights of the film, but even they can do very little with the material at hand. Unless you have a thing for cheap erotic thrillers, there's nothing here.