"Halloween of Horror" is a Halloween-themed episode of the long-running American animated comedy series The Simpsons. It first aired on the Fox network in the United Sates on October 18, 2015. It is the first of two Halloween-themed episodes of The Simpsons that were first shown that year. The second one, "Treehouse of Horror XXVI", first aired a week later. Unlike all previous Halloween-related episodes of the series, there is not much of a fantasy element in "Halloween of Horrors" and its events are considered to be canonical within the regular Simpsons universe.
The episode centers around the character of the 8-year-old girl Lisa Simpson. After becoming extremely frightened during a visit to a Halloween event at a local theme park, Lisa decides that she does not want anything more to do with the holiday. When three men invade her home, Lisa has to overcome her irrational fear of Halloween in order to get out of the very real danger in which she finds herself.
The episode received largely positive reviews. It was nominated for an Emmy for Outstanding Animated Program.
The episode begins on the day before Halloween. The Simpson family have lavishly decorated their home inside and out for the upcoming holiday. They have temporarily changed the name of their house from 742 Evergreen Terrace to Everscream Terrors. The Simpsons' neighbor Ned Flanders asks if they are going to tell three horror stories in a treehouse, as they usually do on Halloween. He is told that the Simpson family are going to do that the following week. The boy Bart Simpson points out to his father Homer that a plastic skeleton has been left too close to a furnace and has melted. The family go off to buy a replacement.
Bart and his sister Lisa see an advertisement for the Halloween Horror Night event to be held at the Krustyland amusement park that evening. Both children are very much looking forward to going to the event.
The family members go to a Halloween pop-up store. It is being run by the local shopkeeper Apu, who is temporarily calling himself A-Boo. Apu yells at three lazy temporary workers who are sleeping on the job. The temporary workers are drifters who wander from town to town working in different holiday pop-up stores. They also try to get high by sniffing the chemicals from everyday objects. Homer's attention is caught by a Mexican Day of the Dead-style decoration which depicts a mariachi skeleton. One of the drifters tells Homer that he can give him a good deal on the decorations. If Homer pays for one of the decorations in cash, the drifter will give him three more for free. The drifter tells Homer not to tell "Old Man Squishee" about the deal. Not realizing that "Old Man Squishee" means Apu, Homer tells Apu about the deal immediately. The three drifters are fired on the spot. They tell Homer that he will be sorry for getting them fired later. Not understanding that he is being threatened, Homer insists that he feels sorry already.
That evening, the Simpson family members go to the Krustyland Halloween Horror Night event. Although she knows that they are only people in costumes, Lisa becomes frightened by the zombies that surround her. She becomes so upset that the attraction has to be temporarily shut down before she is taken home.
The following day, Bart wears his pirate costume to school. Lisa decides that she does not want to wear the Frida Kahlo costume that she worked hard to make and does not want to celebrate Halloween that year. At school, Lisa gets frightened again when she sees the Halloween decorations. Even though they are innocuous and deliberately cute-looking paper representations of ghosts, bats, witches, mummies and Frankenstein's monsters, they make Lisa have flashbacks of her terrifying experience the night before. She hides in her locker and has to be taken home by her mother Marge.
Marge and Homer find out that Lisa has again started clinging to Tailee, a fake fur tail that used to comfort her during her early childhood. Marge realizes that, in order to make Lisa feel more comfortable, all of the Halloween decorations will have to be taken down. She tells Bart that she will take him and his baby sister Maggie to a children's Halloween block party in another part of town. Bart is reluctant to go, until Marge tells him that there will be a model alien there which will repeat any name that a child tells it, even if that name id really a swear word.
Homer tries to bond with Lisa. He says that they can put together a puzzle which depicts two cats playing with a ribbon. The doorbell rings. Thinking that trick-or-treaters will be at the door, Lisa does not want to open it. Homer opens the door. He sees the three drifters wearing masks. They make vague threats. Homer shuts the door in their faces. he notices, however, that the three drifters are continuing to watch the house. Homer becomes increasingly nervous. To calm himself down, he whispers what he calls a "happy tune". He does not appear to realize that he is whistling the theme to John Carpenter's 1978 film Halloween
After a long drive to the block party, Marge is told by a security guard that the party is for residents only. The security guard cannot be bribed and will not allow Marge and her children to enter. Marge begins the long drive back. After a while, she stops the car and tells Bart that he still has some time to go trick-or-treating. The doors of all the house on the street are suddenly locked and their lights suddenly go out. Marge comments that a change is happening. A foot smashing a jack-o-lantern indicates the end of children's Halloween and the start of adults' Halloween. Several costumed adults emerge. They sing about how it is time to wear sexy costumes, flirt and get drunk.
A message, which looks like it is written in blood, tells Homer that the three drifters are inside his house. Not having access to a cell phone and not having paid his phone bill, Homer tries to take Lisa over to the home of their neighbors the Flanders. Lisa realizes that she has left Tailee behind and goes back to get it. Homer runs after her. Back home, they come face to face with the three drifters. Making their way through the fog, caused by one of the drifters trying to get high from a fog machine, Homer and Lisa hide in the attic.
Lisa tries to comfort herself by clutching Tailee and repeating to herself over and over that the danger is not real. Homer tells Lisa that the danger is real. He adds that she will have to use her superior intelligence to think of a way out of it. Lisa says that they can use their decorations for Halloween and other holidays to signal for help. Homer accidentally makes one of the mariachi skeleton decorations play a tune, thus letting the drifters know that he is in the attic. As the drifters enter the attic, Homer and Lisa escape onto the roof.
On the roof, Homer tries to signal for help by lighting some 4th of July fireworks. Unfortunately, his matches keep blowing out in the wind. Lisa tells him that Tailee will burn easily because it is made of polyester and is greasy from years of being handled. Homer lights Tailee before using it to light the fireworks. The adult Halloween revelers hear the fireworks then see the word "HELP" spelled out in lights on the Simpsons' roof. They rush towards the Simpsons' house. The three drifters are arrested. Police Chief Wiggum takes pity on them. He tells them that he can get them a job at a 99 cent store. The three drifters are delighted to hear this.
When Marge, Bart and Maggie finally arrive home, Bart is delighted to see that the Halloween decorations are up again. Marge is shocked. When Lisa emerges from a fake coffin wearing her Frida Kahlo costume, Marge realizes that Lisa is no longer scared of Halloween.
The episode ends with the baby Maggie Simpson finding the burned remains of Tailee. When Maggie picks up Tailee, it magically regenerates in her hand. The theme to John Carpenter's Halloween plays over the credits.