Gomez gets a new carving knife in the mail and has Morticia sharpen it to them. He then goes to work using Fester as a model to carve a jack o'lantern for Halloween that night. Gomez and Fester begin the festivities by playing Bobbing for Apples on a seesaw. When the doorbell rings, Gomez goes to answer it and fester wins. He returns to tell Morticia and Fester that the children are practicing their doorbell ringing for their trick-or-treating. Grandmama and Fester are in the kitchen making punch while Lurch uses a guillotine to make finger sandwiches. Morticia worries that none of the neighbors will come for their party—for the eighth year running—but wants to be ready.
Wednesday comes in wearing her ballerina costume and Fester is terrified of her horrifying costume. When the girl breaks into tears, her parents ask what's wrong and Wednesday tells them that their neighbor Mr. Thompson told her that there's no such thing as witches. Furious, Gomez calls Thompson but the neighbor assumes that he's a nutcases. Even Gomez begins to wonder if Thompson is right, but Morticia assures him that witches exit and shows him Aunt Singe's ashes from when she was burned at Salem.
Gomez figures that they have to show Wednesday the truth and checks the classifieds, but no one is listed. It's too late to place a want ad on short notice, so Morticia proposes that they hold a séance to summon Aunt Singe's spirit and she'll tell Wednesday witches really exist. Grandmama, overhearing, pulls Lurch aside and tells him that spirits and witches are too busy on Halloween to show up on short notice. She tells Lurch to pretend to be Aunt Singe during the séance and he reluctantly agrees.
That night, Cousin Cackle leaves his cave to attend the séance and everyone gathers around the table except Pugsley, who is still out trick-or-treating. Morticia brews a potion to summon Aunt Singe and everyone joins hands. Lurch goes into the next room and speaks through a tube, using a falsetto pretend that he's Aunt Singe. Fester is skeptical and Grandmama tells "Aunt Singe" to knock repeatedly and in different patterns to prove that she's there. A despairing Lurch gives up on that and Wednesday asks Aunt Singe to visit them in person. Realizing he has no choice, Lurch agrees and Gomez congratulates Morticia on the successful séance.
Later, Morticia paints a welcome sign and worries to Gomez that Wednesday might still be disappointed. Grandmama, overhearing them, complains to Lurch that Aunt Singe won't be able to make it and he promised too much. She goes out to see if there are any witches flying around that she can requisition on short notice. As Halloween night draws to a close, Gomez paces nervously and worries that Aunt Singe won't appear. Morticia suggests that they get Wednesday a pet just in case to ease her disappointment, and Gomez returns with a horse. He claims that it's highly intelligent and shows that it can count to zero. Wednesday admits that she would rather have a spider, and Fester is glad to take the horse so he has an excuse to horse-whip Thompson if things don't go well.
Outside, neighbors Penelope and Henry Sandhurst come down the sidewalk, dressed as a witch and a devil. They're on a scavenger hunt because Penelope didn't want to stay at home handing out treats. They split up and Penelope finds herself on the Addamses' doorstep. Lurch assumes that she's a real witch and Grandmama hired her, and escorts Penelope in. Gomez and Morticia figure that it's Aunt Singe, and Wednesday comes in with the welcome sign. Penelope realizes that they've made a mistake and try to leave, but the Addamses insist that she stay.
When Fester and Kitty come in, Penelope faints and Cousin Cackle helpfully tries to wake her up. She sees him and runs out screaming, and the Addamses figure that she had to rush because she has so many Halloween appointments. Grandmama comes in and tells them that Aunt Singe won't be coming, and is surprised to learn that she was already there just long enough to convince Wednesday that witches exist.
Gomez and Fester go back to apple bobbing and the doorbell rings again. Thompson has sent a letter apologizing to Gomez for calling him a nut. He admits that witches do exist because he saw a hideous figure on the roof of their house. The Addamses are glad to learn that they have a resident witch, but Grandmama comes down and assures them that she was just on the roof and there aren't any hideous women there.