The Simpsons hold a séance in hopes of making contact with Maude Flanders. Maude’s ghost materializes and produces a leather-bound book entitled Treehouse of Horror XIII.

Send in the Clones In the first story, Homer is forced to purchase a new hammock when his old one breaks. The peddler who sells him the hammock warns that it is “a mesh of comfort… and evil.” When Homer leaps into the new hammock, it flips him onto the ground and produces a Homer clone. The real Homer realizes the clone is willing to be his slave. Unfortunately the clone accidentally electrocutes itself while changing a floodlight. Homer makes a new clone to help him remove the body. Soon after, Homer makes more clones to do chores around the house, all the while keeping the clones’ existence secret from his family. When one of the clones beheads Ned Flanders, Homer realizes he’s gone too far. He drives the clones to a remote area and begins shooting them. He then drives off, leaving the hammock behind. The surviving clones use the hammock to manufacture thousands of new clones. Ravenous Homers swarm the countryside, devouring everything in sight. Lisa comes up with a plan: the military lures the Homers away by dangling giant donuts from helicopters. The helicopters hover just off a cliff… and the Homers plunge to their deaths. Later Marge realizes the real Homer also fell off the cliff, and she accepts a clone as his substitute.

The Fright To Creep and Scare Harms As Lisa and Bart bury their short-lived pet goldfish, Lisa notices a gravestone that reads “William H. Bonney,” who died in 1881. A second inscription reads, “I dream of a world without guns.” Lisa vows to make his wish come true. Lisa lobbies for a gun-free Springfield, and she eventually achieves her objective. Shortly thereafter Bonney comes back to life and rides into town on a zombie horse. He tells a crowd gathered for an anti-gun rally that he’s better known as Billy the Kid, then introduces the rest of his posse: Frank and Jesse James; the Sundance Kid; and Kaiser Wilhelm. As the undead cowboys terrorize Springfield, Professor Frink pulls Homer aside and proposes a solution to the problem: a time machine will send Homer into the past so that he can prevent guns from being outlawed. The time machine transports Homer to the anti-gun rally several days earlier. Homer and a supportive crowd use their guns to chase the zombie cowboys out of town. Moments later another Future Homer materializes and warns that gun violence will destroy the Earth. Moe shoots him dead.

The Island of Dr. Hibbert The Simpsons decide to spend their vacation at The Island of Lost Souls. Dr. Hibbert welcomes the family as a dog-like Groundskeeper Willie picks up their luggage. During dinner the family is fed a large turkey that has a remarkable resemblance to Professor Frink. That night Marge voices her concern to Homer and sets out to investigate. Dr. Hibbert comes up behind her and plunges a hypodermic needle into her arm. When Marge returns to bed she is half-woman, half-cat. Realizing what’s happened, Homer vows to save Marge… only to realize that Bart and Lisa have disappeared. He rides a half-human, half-cow Flanders into the jungle, where he discovers more of the “manimals,” including Anteater Maggie, Spider Bart, and Owl Lisa. Homer tries to rally the monsters and form a rebellion, but they realize they’re better off the way they are. Homer decides to join suit… and is transformed into a walrus.