The Adventures of Buckaroo Banzai Across the 8th Dimension

Buckaroo Banzai and his mentor Dr. Tohichi Hikita perfect the "oscillation overthruster", a device that allows an object to pass through solid matter. Banzai tests it by driving his Jet Car through a mountain. While in transit, he finds himself in another dimension. After exiting the mountain and returning to his normal dimension, he discovers an alien organism has attached itself to his car.

Dr. Emilio Lizardo, incarcerated at the Trenton Home for the Criminally Insane, sees a television news story of Banzai's successful test. In 1938, Drs. Lizardo and Hikita had built a prototype overthruster, but he tested it before it was ready and became stuck between dimensions. He was attacked by aliens until freed by his colleagues, emerging changed and violent. Understanding that Banzai has finally accessed the 8th dimension, Lizardo escapes the asylum and plots to steal the overthruster.