The Simpsons go to Diz-Nee-Land. After a really long journey, they dislike all of the lame rides they visit, and decide to go to "Rocket to Your Doom", a just-opened queue-less ride which wasn't on the map. They get in and it immediately transforms into a space ship. At first, the family is skeptical, but a screen appears with Kang and Kodos on it telling them that they are being taken to their home planet Rigel 7. At the planet, Kang and Kodos show them around in a giant pet cage and the Simpsons are informed they are prisoners. Then they are taken as exhibitions to a zoo. After a while, they are informed they must choose one of them to be dined in a ritual. Everybody votes for Homer (even he changes his vote from Bart to himself after seeing the other votes).
Afterwards, we can see Homer walking in something that looks like bacon underwear, to be eaten, but he gets rescued by some hippie-looking Rigelians who believe that eating other sentient species is wrong. After an excessive party, he gets on another space ship only for one that also pleases all desires, but he realizes he won't enjoy it without his family and goes back to rescue them. The Rigelians have decided to eat the rest of the family and they are glazed over giant plates with some lettuce and tomato. When Homer offers to be eaten instead, he gets put on a similar plate and annoys the Rigelian chef by eating the glaze and claiming he didn't get any. The Rigelian Queen then eats Homer's previously off-camera severed buttock and gets poisoned because of the fast food life they all lead; even Lisa is the most polluted of them all and would be better chewing tobacco like Bart. The Rigelian Queen dies from the poison.
Following the Rigelian Queen's death, the Simpsons get sent home on a space ship that looks like the interior of the original starship USS Enterprise. They set course to Earth. But after a call from Grampa Simpson, the family decides to go anywhere else but home.
The credits happen over a montage of several images spoofing Star Trek TV and film franchise scenes.