On his 168th birthday, Dr. Fu Manchu (Sellers) is set to take a dose of his age-regressing Elixir Vitae. Unfortunately, an incompetent henchman sets himself on fire and uses the elixir to douse the flames, leaving the supervillain with only a few months to gather enough diamonds to create a new elixir. Fu Manchu soon targets the crown jewels of the British Royal Family, and Scotland Yard calls his old rival, Nayland Smith (also Sellers) out of retirement. Smith has gone a little... odd as a result of a previous period of being captured and tortured by his nemesis, but he comes up with a plan to save the jewels, including having a talented policewoman, Alice Rage (Helen Mirren) impersonate the Queen.
This film provides examples of:
- Bad Boss: In addition to having at least two henchmen executed for their various failures, it turns out that Fu Manchu doesn't even pay his subordinates, forcing him to actually start paying them just to that he can fine them when they screw up again.
- The Bad Guy Wins: Fu Manchu steals all the diamonds, rejuvenates himself and even manages to snag himself a hot girlfriend, with Nayland Smith only managing to temporarily inconvenience him. Having said that, Smith does succeed in retrieving everything else that the doctor stole... mostly because he decided to just give back all the stuff he didn't need.
- The Cameo: Burt Kwouk, who co-starred with Sellers as Kato in the Pink Panther films, makes a brief appearance at the start of the film, during which Fu Manchu tells him, "Your face is familiar."
- Cloud Cuckoolander: As a result of years of torture at Fu Manchu's hands, Nayland Smith insists on keeping a lawnmower with him at all times. Fu Manchu is even able to take him out of commission for a large portion of the movie by stealing the mower.
- FaceHeel Turn: After being captured, Alice suddenly falls deeply in love with Fu Manchu for some reason (loosely implied to be a shared love of musical theatre) and helps him steal the crown jewels.
- Gainax Ending: Things get very strange in the last fifteen minutes or so, which has Nayland Smith's house suddenly sprouting a hot air balloon, flying to China, and then Smith for some reason just giving Fu Manchu the diamond he needs to finish the Elixir Vitae. The strangeness then gets turned Up to Eleven in the final moments, when the rejuvenated Fu Manchu suddenly performs a rock musical number.
- Honey Trap: Subverted; though Alice Rage is wearing a sexy outfit when she seduces the Tower of London's chief guard into helping them steal the crown jewels, she actually seduces him via his love of Chinese food and provides a huge banquet of the stuff.
- Idiot Ball: After the villain fails to steal the crown jewel diamond (because it had been replaced with a replica before the theft) Nayland Smith decides to pay him a visit, bringing the real diamond along. And then he hands it over without much fuss.
- The Jeeves: Perkins, Nayland Smith's live-in butler. For the most part he's a straightforward example of this trope, but he shows a less common skill when he pilots Smith's house-airship to China.
- Ms. Fanservice: Alice Rage, particularly in her introduction scene where she performs a song and dance routine in a very skimpy outfit.
- Suspiciously Similar Substitute: Sellers' version of Nayland Smith is basically Inspector Clouseau, except English, older and a little less incompetent.
- Villain Protagonist: The film is very much Fu Manchu's story, with Nayland Smith just being a bystander for the most part.
- Worthy Opponent: Fu Manchu acknowledges Nayland Smith as this near the end of the movie, and even gives him his own supply of Elixir Vitae so that they can continue their rivalry for decades to come.
- Yellow Face: Surprisingly enough, played completely straight. The film never once lampshades or even acknowledges the fact that Fu Manchu is being played by a white man in heavy make-up.
- You Have Failed Me: The henchman who wastes the original supply of Elixir Vitae gets tortured and buried alive for his troubles.