As Powerhouse plays in the background (and will play repeatedly in the short), Marvin the Martian (here referred to as Commander of the X2 vessel) is traveling to Earth. Upon landing, he opens his assignment envelope - return one Earth creature back to Mars (signed, Commander E=mc²). With the help of his martian dog, K-9 (who 'talks' to Marvin by handing him notes), he finds Bugs' rabbit hole. As the two observe the hole, they are pushed back when Bugs cleans out a bucket of carrot stems. Seeing their getup, Bugs assumes it must be Halloween, so he hands them each a bag of treats. Marvin then decides that he'll have to use force. He pulls out his disintegrating gun and atomizes a large hole where the small rabbit hole used to be. Bugs shrieks "How Halloween-y can you get?" before seeing the flying saucer.
Marvin then tells Bugs that he's to come back to Mars with him. Bugs tries to act defiant, but goes slightly insane when Marvin uses his pistol against a nearby rock (which also disintegrates part of the ground under the rock). He quickly gets some bags and runs into the ship, then runs back out as a train conductor, telling Marvin and K-9 "Flying saucer, leaving for Saturn, Neptune, Jupiter, Venus, the Dogstar and Mars now leaving on track five! All aboard!" Marvin and K-9 rush on the ship and fly off, then realize their mistake in midflight and fly back ("Oh! That wasn't a bit nice! [huff, puff] You have made me very angry, [huff, puff] very angry indeed!").
Bugs convinces Marvin that he wants to go to Mars, but he doesn't want to get involved in a mutiny (the implication that K-9 is going against Marvin). Marvin calls K-9 over and atomizes him, but K-9 pulls himself out of his helmet, asking what he did wrong (signed, 'Anxious'). Bugs starts walking off, but Marvin and K-9 shoot him with an Acme Straight-jacket ejecting bazooka, tying Bugs up. On the ship, Marvin is piloting while K-9 watches over Bugs (labeled as "One over-confident Earth creature"). Bugs convinces K-9 to let him 'try on something more sporty - say in a size 36'. Now out of the straight-jacket, Bugs quickly ties K-9 up, then grabs another jacket and yells that the ship has struck an iceberg, quickly tying up Marvin as well (telling Marvin it's a life preserver).
Now with both of them tied up (labeled as "Two disgruntled Martians"), Bugs tries turning the ship back home. After a brief out-of-control spin, he starts to fly back, but throws out an anchor to steady the ship. The anchor then pulls on a crescent moon, which in turn pulls on Saturn's rings, a large planet (presumably Jupiter) and other assorted stars. Back on Earth, a small man in an observatory looks into his telescope, only to see the spaceship and the planets directly in front of him. The man then writes a note ("I resign! When I begin to see things like this, it's time to take up turkey farming." Signed, I. Frisby (a reference to Friz Freleng, whose caricature was indeed used for the character) and leaves. Outside, Bugs asks the man if he knows where he can sell a "slightly used flying saucer — it's only got 3 billion miles on it." The man then starts making spastic movements and walking off, causing Bugs to ask the audience,:"Huh, what's biting him?"