A group of 21st-century colonists inhabit an underwater city called Pacifica. Originally intended as a purely scientific installation, the U. S. government wants to stash all its gold reserves from Fort Knox there, along with a fantastic new radioactive element. The brother of Pacifica's returning former commander plans to steal the gold and on top of that, the city faces destruction by an asteroid from outer space!

After moving to Pasadena, Texas, country boy Bud Davis starts hanging around a bar called Gilley's, where he falls in love with Sissy, a cowgirl who believes the sexes are equal. They eventually marry, but their relationship is turbulent due to Bud's traditional view of gender roles. Jealousy over his rival leads to their separation, but Bud attempts to win Sissy back by triumphing at Gilley's mechanical bull-riding competition.