Description
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 success. In 1938, he and Hikita had built a prototype overthruster, but he tested it before it was ready and became stuck between dimensions. Though eventually freed, he was attacked by aliens while stuck between dimensions. Realizing that Banzai has successfully infiltrated the 8th dimension, Lizardo escapes the asylum.
Banzai and his band, "The Hong Kong Cavaliers," are performing at a nightclub when Banzai interrupts their musical intro to address a depressed woman in the audience, Penny Priddy. During a song he performs especially for her, she attempts suicide, which is mistaken for an assassination attempt on Banzai. After bailing her out of jail, he realizes she is his late wife's long-lost twin sister. Later, during a press conference to discuss his rocket car experience, the overthruster, and the specimen of alien/transdimensional life he obtained while traversing the 8th dimension, Banzai is dispatched to the phone, where he receives an electrical shock. Simultaneously, strange men disrupt the event and kidnap Hikita. When Banzai returns, his electrical shock enables him to recognize them as reptilian humanoids, and he gives chase. He rescues Hikita and they manage to evade the men long enough for the Cavaliers to rescue them.
Banzai and the Cavaliers return to the Banzai Institute, where they are met by John Parker, a messenger from John Emdall, the leader of the peaceful Black Lectroids of Planet 10. Emdall, currently in Earth's orbit, explains that they had been at war with the hostile Red Lectroids for years, managing to banish them to the eighth dimension. Lizardo's failed test of the overthruster in 1938 allowed the Lectroids' leader, John Whorfin, to take over Lizardo's mind and enable several dozen others to escape. Because Banzai has perfected the overthruster, Emdall fears Whorfin and his allies will try to acquire it to free the other Red Lectroids and tasks Banzai with stopping Whorfin; otherwise, the Black Lectroids will fake a nuclear explosion in Russia to trigger an atomic war, annihilating the Red Lectroids on Earth in the ensuing World War III.
The Cavaliers track the Red Lectroids to Yoyodyne Propulsion Systems in New Jersey. They realize that Orson Welles's broadcast of The War of the Worlds described the Lectroids' arrival in 1938, though afterward the Lectroids forced him to state it was fictional. Yoyodyne has been building a spacecraft to cross over to the eighth dimension, disguised as a new United States Air Force bomber. While the Cavaliers are planning their response, Red Lectroids break into the Institute and kidnap Penny and (unbeknownst to the Red Lectroids) the overthruster, which she was carrying.
At Yoyodyne, Penny refuses to tell the Red Lectroids where the overthruster is, and they begin torturing her. Banzai enters Yoyodyne headquarters alone; the Cavaliers follow, reinforced by several groups of the Blue Blaze Irregulars, youngsters recruited to assist the Cavaliers when necessary. Banzai saves Penny and fights off the Red Lectroids, though she is wounded and unconscious. While the Cavaliers tend to her, Banzai and Parker sneak into a pod on the spacecraft. Lacking Banzai's overthruster, Whorfin insists they use his imperfect model, which fails to make the dimensional transition; instead, the Red Lectroid spaceship breaks through the Yoyodyne wall and takes off into the atmosphere. Lord Whorfin ejects the pod containing the pair from the craft, but they manage to activate it and use its weapon systems to destroy Whorfin and the other Red Lectroids. Banzai parachutes back to Earth while Parker returns to his people in the pod. With the situation resolved and war averted, Banzai finds Penny has died from her injuries. When he goes to give her a final kiss, Emdall gives Banzai another brief shock, thus reviving Penny.
