On Treehouse of Horror VII, Bart and Lisa hear strange noises coming from the attic and Kang and Kodos try to take over the Earth.

The 7th Treehouse of Horror opens with Homer accidentally setting himself on fire while trying to light a Jack-O-Lantern.

The Thing and I

Bart and Lisa begin hearing strange noises coming from the attic. Homer denies anything is wrong, but at breakfast he takes fish heads upstairs to feed something. Seeing this, Lisa and Bart investigate the attic when Homer and Marge are out of the house. It turns out there really is something in the attic. Returning home, they all scream to their parents about what they saw. Homer and Marge check the attic and are horrified to discover whatever was in there has escaped.

Marge immediately calls Dr. Hibbert and tells him that Hugo is loose. It turns out that Hugo is actually Bart’s twin brother. Dr. Hibbert also explains that Bart and Hugo were born as conjoined twins and one of them was evil. Bart and Hugo were surgically separated after birth, with Bart being given to Marge and Hugo being placed in the attic so he couldn’t cause any damage.

While everyone else leaves to go find Hugo, Bart stays put at home. Bart realizes Hugo is still in the house and soon after is taken to the attic because Hugo hopes to sew the two of them back together. Dr Hibbert manages to stop Hugo in time and eventually comments how the left twin is always usually the evil one. But while checking Hugo’s surgical scar, Dr. Hibbert realizes that he can’t have been the left twin. Which means that Bart is and always was the evil twin. To remedy the problem, they make the twins switch places and now Bart lives in the attic.

The Genesis Tub

As part of a science project, Lisa tries to find out if cola will dissolve a tooth. While in the middle of setting up the experiment, Bart walks in having created static from a balloon and shocks her. She ends up transferring the shock when she touches the tooth in the cola before going to bed. Waking up the next morning, she thinks she sees mold on the tooth. But using her microscope, Lisa sees that it’s actually tiny forms of life she’s created.

Ecstatic that she’s created miniature people, Lisa briefly heads down to breakfast before checking again on her creation. It turns out that they’re evolving at an incredible pace and it isn’t long before the miniature life forms have created a futuristic society. But Bart steps in and messes with the tiny civilization by poking at it. Later that night, tiny space ships fly up from the tub and attack Bart.

Furious at this, Bart tries to get even and promises he’ll destroy the civilization when Lisa isn’t around. However, the tiny civilization winds up shrinking Lisa down to their size and brings her inside their World. They view her as their creator and god and Bart as the devil. Lisa promises she can take care of things if they put her back to her normal size, but it seems they don’t have the technology to do that yet. Which means all she can do is watch as Bart takes the tiny universe, enters it into the school science fair, and wins first prize.

In response, Lisa decides to have the people she created grovel and bring her some shoes.

Citizen Kang

While fishing, Homer gets abducted by Kang and Kodos. Demanding they take him to Earth’s leader, Homer tells them it’s President Bill Clinton, but also adds that since an election is about to take place, it might also be Bob Dole.

Kang and Kodos abduct both men and after putting them in tubes for storage, transform themselves into the Bob Dole (Kang) and President Clinton (Kodos). The aliens spray him with rum so that no one believes his story and return him to Earth, while they pretend to be presidential candidates. Their unusual behavior is noted by some, but Homer’s efforts to warn people come to nothing.

But when Homer finds the alien spaceship, he has a chance to fight back. Managing to talk to the real Bob Dole and President Clinton, the two men agree to put their differences aside to fight the aliens. But this doesn’t happen because Homer accidentally presses the wrong button and propels them out into space. Coming up with a new idea, Homer crashes the ship into the capital building during a rally and rips off the alien’s disguises in front of everyone.

Undeterred, the aliens laugh and remind the people of Earth that based on their system of government, one of them will end up winning. That turns out to be Kang who promptly enslaves everyone. Treehouse of Horror VII ends with Homer reminded Marge “Don’t blame me, I voted for Kodos.”