The destination of every Woody Allen plot is exactly the same: Woody bones a hot young woman that he has no right boning. All other events exist to bring things to that foregone conclusion.
In Curse of the Jade Scorpion, the events that bring us there aren't nearly as entertaining as they want to be. Allen plays his usual riff on his 60-year-old neurotic, womanizing self, this time as C.W. Briggs, a claims investigator for a large insurance agency. We quickly learn that Briggs is feeling especially neurotic because his agency has hired an efficiency expert named Ms. Fitzgerald (Helen Hunt), who has been making changes around the office that don't mesh with Briggs' old-fashioned style. The two hate each other, and many less than funny insults are exchanged between them throughout the movie.
The challenge for Allen the filmmaker is thus to change Briggs' relationship with Fitzgerald from malice to boneage, and he does so by way of a hypnotism demonstration that the two find themselves attending simultaneously.
Stop reading and guess what happens next.
Now read on: they are both selected to be hypnotized, the hypnotist decides to be cute and hypnotizes them to think they are in love, and when the show is over, we learn that certain "elements" of the hypnotic spell are still hangin' around. Was your guess right? Mine sure was.
There are other twists as well. The hypnotist turns out to be a jewel thief who uses his powers to make people steal for him. Briggs and Fitzgerald are of course his latest victims and presto: Wacky antics ensue. It all feels tired, though. Twisty plots aren't Allen's style. His foregone conclusion works best when the events leading to it are complicated by real relationships, not gimmicky story contrivances.
Save your money and go rent Manhattan. It was made during a time when Allen still loved his characters, and he was only in his 30s, so it was at least plausible that he could achieve boneage with Diane Keaton.