Princess Vespa (Daphne Zuniga), Daughter of Roland, King of the Druids, runs away from home on her wedding day and, seeing an opportunity, the evil Spaceballs snatch her up. King Roland hires journeyman space pilot Lone Star (Bill Pullman) and his cohort Barf (John Candy) to bring Vespa home, but they have a huge challenge ahead of them. The Spaceballs are led by Dark Helmet (Rick Moranis), the evil commander dressed in black who has attained vast amounts of money and power. All this despite the fact he's the shortest guy on his ship and can't breathe inside his helmet.
Still, Dark Helmet must answer to President Skroob (Mel Brooks) and command his ship, all while trying to seduce the Princess. Eventually, she escapes with Lone Star and the chase is on. Dark Helmet would have more luck finding the princess if he wasn't surrounded by assholes. He does not suffer their incompetence, however, and threatens to inflict great pain on the (Space)balls of any man who fails to do their job. So, at least his crew is motivated.
Ultimately, Dark Helmet and Lone Star face off against each other for the first time for the last time. Dark Helmet tricks the naive Lone Star into giving up his Schwartz, but as we all know, the Schwartz cannot be stored inside of a ring or a medallion, but inside all of us... or something like that. The point is that Lone Star proves his worth as his true lineage is revealed. He is a prince and therefore free to marry Princess Vespa. Dark Helmet, on the other hand, finds himself marooned on a strange planet with the President and his top Colonel after blowing up his own ship. There goes the planet, indeed.
Dark Helmet uses fear to keep his crew in line and to run whatever parts of the galaxy he can, but the insolence of a few rebels are enough to scuttle his great plans for universal conquest. He may be ruthless and power hungry, but he isn't the brilliant or - ahem - tall maniac one might fear. But then again, this is Spaceballs, and for the citizens of this universe, he's the worst that they've got.