Plot hole?
At the end Warwick, having been basically found out, invites the detective over for dinner and the movie implies this is a horrific thing. Why? All Warwick does is drug his victims and put makeup on them, then toss them onto the footpath so they wake up. They don't even have amnesia.
So...the dective will go thru the same process as John....drugged, emotionally abused, made up, then tossed out. Next day the detective will wake up and Warwick will go to prison. Pointless.