The movie stars Peter Weller as Buckaroo Banzai, a neurosurgeon, physicist, and rock musician, who along with his team of eccentric comrades known as the Hong Kong Cavaliers, embark on a mission to save the world from an invasion of evil aliens from the 8th dimension. These aliens are led by the evil Dr. Emilio Lizardo, who has possessed the body of Buckaroo's mentor, Dr. Hikita.
Buckaroo and his team utilize their various skills and gadgets to thwart the aliens' plans, but they soon realize that the invasion is only a small part of a larger plot to take over the world. In their journey, they encounter many strange characters, including an alien named John Whorfin, a scientist named Dr. Sidney Zweibel, and a femme fatale named Penny Priddy, who turns out to be the long-lost twin sister of Buckaroo's deceased love interest.
The film is a zany blend of science fiction, action, and comedy, with a quirky style and unique visuals. Its eccentric characters and bizarre storyline have made it a cult classic among fans of the genre.