- "No, no, no, no! Light speed's too slow! Yes, we're gonna have to go right to... Ludicrous speed!"
- ―Dark Helmet[src]
On Planet Druidia, Princess Vespa is about to get married to Prince Valium (who is the last known prince in the galaxy, and thus they have to marry despite his characteristics). In a fit of rebellion, she runs off from the altar with her droid-in-waiting, Dot Matrix, and escapes into space.
Planet Spaceball has foolishly wasted all of its oxygen and is desperate to find more. President Skroob and his top military leader, Dark Helmet (along with his aide Colonel Sandurz), devise a plan to kidnap Princess Vespa and extort Planet Druidia into giving all of its air to Planet Spaceball. As luck would have it, they come across the fleeing princess shortly afterwards, firing a barrage of nearly-botched "warning shots" and provoking the princess to contact her father for help. Dark Helmet playing with his dolls againMeanwhile, Vespa's father, King Roland hires two mercenaries—Captain Lone Starr and Barf (a mawg, or man-dog halfbreed) to rescue his daughter and bring her back to the wedding. The pair, desperate for money to pay back their debts to mafia boss Pizza the Hutt, agree. They are later helped by the wise alien sage known as Yoghurt and the mysterious power he possesses, called the Schwartz.
In the end, Lone Starr and Barf are able to rescue the princess, destroy the Spaceballs' spaceship, and get the Druidian air back. And at the very end Lone Starr, having found out he is a prince as well and, marries Vespa. Pizza the Hutt gets locked in his car and eats himself to death. As for Skroob, Dark Helmet, and Colonel Sandurz, they survive a crash-landing on the Planet of the Apes.