Adventurer/surgeon/rock musician Buckaroo Banzai and his band of men, the Hong Kong Cavaliers, take on evil alien invaders from the 8th dimension.
Toxic waste dumping in a small Idaho town turns a young boy into horrible mutant monster. The town's police chief and a government scientist team up to stop the monster, which is quickly killing off the town's citizenry.
Philo takes part in a bare knuckle fight - as he does - to make some more money than he can earn from his car repair business. He decides to retire from fighting, but when the Mafia come along and arrange another fight, he is pushed into it. A motorcycle gang and an orangutan called Clyde all add to the 'fun'.