A bus driver informs the passengers that there are rumours of a witch, but everyone knows that witches aren't real... yet, he's proven wrong when a witch flies by, accompanied by flying goblins. The witch and her goblins scare the people in the bus, take off the wheels, and hold the driver up and threaten him.
Meanwhile, most of the Ghostbusters are going to bed, but Egon is doing an experiment and Slimer is watching. Whatever Egon's working on blows up, sending his chair flying backwards. He then explains that he got distracted after an image of an ugly old woman entered his mind. Peter thinks Egon hallucinated from overwork, but Egon doesn't think so. The phone rings, asking if they "do" witches and goblins. Peter and Slimer are sure it's a hoax, but agree when they're offered double pay.
They meet a woman, who wants the witch dealt with before the upcoming pilgrim festival. Slimer goes to an ice cream store, when he sees several men there who all look just like Egon. The woman leaves, and Slimer shows the guys the Egon lookalikes. Then, they all notice a statue nearby looks just like him too. The statue, as it turns out, is of a man named Eli Spengler, who apparently ended witchcraft 300 years ago. Egon reveals that he's his great-great-great-grandfather, but he always thought his grandma had made him up.
Slimer scans the area, and does find spectral activity, but then the goblins steal the scanner. The Ghostbusters attack them, then the witch appears. She grabs the woman, flies around with her, and swears revenge on Egon for Eli trapping her. He recognises her as the hag he saw in his "hallucination".
In the car, it's revealed that the witch's name is Kestrel, and she used to be a noncorporeal demon, who possessed people and made them do "terrible things". They arrive at a girls' school, but the headmistress kicks them out so the students can study.
The Ghostbusters get a high reading from a pit full of ruins, so they investigate, with Slimer accompanying them. Peter finds a large, glowing crystal and they're about to leave with it, when a goblin in a digger dumps dirt on them. Slimer distracts the goblin while the guys climb out. The goblins attack and one of them tries to steal the crystal. When the goblins leave, Egon (whose glasses were stolen so he puts on safety goggles) tries to do tests on the crystal, but Slimer is sucked into it. He flies out, but Egon determines that it's half of a containment device, and the other half is out there somewhere.
The Ghostbusters tell the headmistress that a student may be possessed and ask permission to scan the girls, but she still says no because she doesn't want the girls distracted. So, Peter and Egon decide to dress in drag and work undercover. Ray, disguised as a janitor, makes a purple liquid, and Winston, disguised as a sports coach, sees over some girls racing.
Kestrel then possesses the headmistress. Ray sees the possessed headmistress and alerts the others, and they all follow her into the basement. There, Kestrel, the goblins, and a hoard of brainwashed citizens are making a potion with which to destroy the town. She adds Egon's glasses into the potion.
Then, the Ghostbusters change back into their uniforms, while Kestrel flies out of the headmistress's body and changes back into noncorporeal form. The Ghostbusters break into the school and trap a bunch of goblins, but then Kestrel possesses Egon. The possessed Egon takes the second half of the crystal and throws stuff at the non-Egon Ghostbusters, then Ray tries to throw the purple potion he made at him/her, but the possessed Egon flies away on a broom. He/she then goes to the car, steals the other crystal half, and flies off.
At the statue, Kestrel/Egon is about to stick the crystal halves together. Winston and Peter fight off the remaining goblins, while Ray goes to make more potion. Kestrel/Egon then sticks the crystal together and uses it to teleport the brainwashed citizens near. Ray then uses the potion to exorcise Egon, who picks up the crystal and uses it to suck up Kestrel and the goblins. Then, the pilgrim fest happens as usual, but Peter is confused because several people dress as Egon. Then, he does.
This episode provides examples of
- Agony of the Feet: Peter stubs his toe on the crystal.
- Arbitrary Skepticism: Peter and Slimer, despite knowing of the existence of ghosts, demons, etc. don't believe in witches or goblins.
- Blind Without 'Em: When Egon's glasses are knocked off, he complains he can't see.
- Copycat Mockery: When Winston says, "Oh no!", Kestrel-in-Egon's-body copies him back to tease him.
- Demonic Possession: Discussed when Ray reveals that before becoming a witch, Kestrel was a demon who'd possess people and make them do misdeeds. Later played straight when she possesses the headmistress, then later, Egon.
- Disguised in Drag: Because the school is for girls only, Peter and Egon have to dress in drag to disguise themselves as students so they can work undercover to avoid distracting the girls.
- Donut Mess with a Cop: Discussed when Peter says he and the others will stick to Egon like cops to a donut shop.
- Dramatic Irony: Peter and Slimer express doubt about the witch and the goblins existing long after we've already seen them all.
- Ectoplasm: Slimer gets slime on the Ghostbusters when demonstrating how Egon's experiment blew up.
- Evil Laugh: Kestrel laughs maniacally many times.
- Evil Wears Black: Kestrel, a vengeful witch, wears a black hat, cloak, and dress.
- Flying Broomstick: Kestrel flies on a broom.
- Get Out!: The headmistress bluntly insists the Ghostbusters leave the school so the girls can study.
- The Hyena: Kestrel is prone to shrill, evil laughter.
- Instantly Proven Wrong: Kestrel shows up just after the bus driver says witches are a myth.
- Last-Name Basis: Kestrel addresses Egon by his last name.
- Mistaken for Flirting: Peter somehow concludes that the headmistress is "crazy" about him, even after she throws him and the others out of the school.
- Mistaken Identity: At the end, Peter mistakes a woman in an Egon mask for the real Egon.
- Mythology Gag: Peter calls Slimer a "spud", which is what Ray called him in the movie.
- Not So Stoic: Egon screams when he's sent backwards on his chair.
- Oh, Crap!: Slimer screams upon noticing that Egon is possessed.
- Only in It for the Money: Peter and Slimer only agreed to accompany the others on the mission so they'd get double pay, since they didn't even believe in witches or goblins.
- Pun: When complaining about having to dress as a teenage girl, Peter calls it a "real drag".
- Pun-Based Title: The title is a pun on "witch" and "rich".
- Running Gag: Peter keeps wishing that the conflict had been caused by "swamp gas".
- Shared Family Quirks: Eli was apparently related to the Spenglers and was also a paranormal eliminator like Egon.
- Sins of Our Fathers: After being freed from Eli's imprisonment, Kestrel wants to get her revenge on Egon for being his great-great-great-grandson, and on various other relatives of his.
- Skewed Priorities: The headmistress still won't let the Ghostbusters interrupt the girls' studies, even when learning that one might be possessed.
- Terms of Endangerment: Kestrel threatens the bus driver and calls him "old friend".
- Transformation of the Possessed: Anyone who Kestrel possesses turns into an old witch.
- Vocal Dissonance: Peter and Egon use their normal voices when disguised as teenage girls.
- Witch Hunt: Eli Spengler apparently ended witchcraft.
