The Ghostbusters, Janine, and Slimer are watching the news, which concerns a freak tornado in Central Park. Egon does an equation and determines that the "tornado" is actually not one, but he has no clue what it actually is.
Determined to find out, he drives off with the rest of the Ghostbusters plus Slimer, to central park, where the "tornado" is still going. Egon studies it and finds out that it is indeed not a tornado, and not only that but there's a high PKE reading. His friends tell him to move farther away, but before he can, he's pulled into it. The others try to save him, but it doesn't work, and Peter and Ray are pulled in too. Then, the anomaly disappears. Winston fails to contact the others, so Slimer cries, but Winston is sure they'll get them back even if he doesn't know how.
The rest of the Ghostbusters appear to land in NYC, but it's inexplicably dark. Ray checks the time, but his watch keeps changing unreliably, then dies. Ray tries to contact Winston, but it also doesn't work.
They go home, only to find that instead of a ghost, the sign on the firehouse now has a picture of Egon on the "no" sign. The firehouse itself is very dusty, and Winston is nowhere to be seen. They see someone is messily raiding the fridge and presume this is Slimer, but it's a tentacled monster instead.
They enter the bedroom and find someone sleeping in what's supposed to be Peter's bed. Peter thinks this is Winston and goes to wake him up, but it's instead an undead man who looks like Peter. Then, an undead Egon and Ray appear. The three undead men threaten the living men with guns that launch slime, so the non-Winston Ghostbusters open fire on their counterparts. It doesn't work, and the undead guys start firing slime at the living guys.
They run downstairs, where an undead Janine is working and reveals over the phone that the undead versions of the Ghostbusters are called the "Peoplebusters". She screams at the sight of living people, and the Ghostbusters run outside, where they start floating. Then, they see a sign saying, "Welcome to Boo York, the Big Pumpkin", confirming that they're in a parallel universe version of New York where everyone's a ghost. Then, the Peoplebusters chase after them in a crazy-looking car.
Back in the normal universe, Winston and Slimer tell Janine about the others disappearing. Meanwhile, the other Ghostbusters are still on the run from the Peoplebusters, and they scare whoever sees them. Then, the Peoplebusters blast Ray with slime until he's immobilised and Undead Ray takes him away. The other two Peoplebusters continue to chase Peter and Egon.
Back at home, Winston, Janine, and Slimer have souped up a communication device to try and reach the others, but it doesn't work. Peter and Ray hide on a big statue, where they're pursued by the Peoplebusters in a flying machine. They stop to catch their breath, dead-set on retrieving Ray, but then Egon falls through the wall. Peter reaches out and falls through the wall too.
They find themselves in a salon, where a hairdresser scares a ghost with a photo of Egon to make her hair stand on end so she can cut it. The Peoplebuster versions of Egon and Peter enter and search, finding them when Egon gets some hair up his nose and sneezes. Peter and Egon run, but the Peoplebusters nab Egon.
Janine, Winston, and Slimer keep trying to communicate with the other Ghostbusters, and they finally get a link when Slimer touches the machine. With the whole firehouse population finally linked, they all have a conversation, and it turns out Ray and Egon are locked up but in quite an idyllic place. Peter describes the alternate world as the opposite of the normal world, so Winston wonders if the prison is the doorway to "reality".
They ask Peter to let himself be caught, which he does, and they find more people who accidentally found themselves in Boo York. They find a portal and try to go through it, but it doesn't work, so they try firing at it.
The Peoplebusters realise there's a breach when an alarm sounds, so they enter the prison. The non-Winston Ghostbusters fire back, trapping the Peoplebusters in their own slime, then escape and land back in Central Park. Winston, Janine, and Slimer drive up and welcome them back.
This episode provides examples of
- Back from the Dead: Discussed when the ghost barber jokes that his work might make him live, the reverse of a human complaining that their job is killing them.
- Badass in Distress: Peter, Ray, and Egon end up stuck in a parallel universe and chased by ghosts who are trained to hunt down people.
- Bait-and-Switch: The first scene appears to be outside, but it turns out to be on TV.
- Balloon Belly: Slimer gets fat when he drinks all the juice from a watermelon. Possibly justified because he's a ghost.
- Bizarro Universe: Peter describes the alternate world as being the reverse of the normal world.
- Covered in Gunge: The way the Peoplebusters catch people is by coating them in ectoplasm until they can't move.
- Demonic Possession: Discussed by Egon, who states that whatever is causing the situation isn't demonic possession.
- Did You Just Flip Off Cthulhu?: When Undead Ray says that the non-Winston Ghostbusters "made a big mistake", Peter replies, "Your mistake, ghost breath; we live here!".
- Ectoplasm:
- Exploited — the weapons in the other world run on green, supernatural slime.
- Played for laughs when Slimer kisses Peter and leaves slime on his face.
- Eldritch Location: Boo York gives humans the ability to fly.
- Fantastic Racism: These undead people dislike humans and formed an organisation called the "Peoplebusters" (unlike the Ghostbusters, they attack all people on sight, whereas the Ghostbusters tend to only target evil or destructive ghosts).
- Fat Bastard: Undead Ray is a lot fatter than the real Ray, and he antagonises humans.
- Flight: Humans can fly in Boo York.
- Green and Mean: A few of the person-hating ghosts are green.
- He's Got a Weapon!: When the undead versions of Peter, Ray, and Egon whip out their slime guns, Peter says in confusion, "They have guns!".
- Hoist by His Own Petard: The non-Winston Ghostbusters end up trapping the Peoplebusters in their own slime.
- Hold Your Hippogriffs: One of the Peoplebusters says it's nice to have things back to "abnormal" again.
- Horrifying the Horror: The mere sight of people causes most of the ghosts in Boo York to run off screaming.
- Ill-Timed Sneeze: The undead versions of Peter and Egon find their living counterparts when they're hiding, because Egon sneezes due to some hair irritating his nose.
- Joke and Receive: Subverted — When Janine points out the weirdness of a tornado in Manhattan, Winston says, "Yeah, what's next, earthquakes?" — and then one apparently does occur, but then it turns out that this was not an earthquake; Slimer just burped.
- Leaning on the Fourth Wall: One of the Peoplebusters references the line "I ain't afraid of no ghosts" from the theme song by saying, "We ain't afraid of no people".
- Losing Your Head: Some of the ghosts have their heads taken off to have their hair done.
- Mirror Universe: In this universe, the Ghostbusters' counterparts are villains who hunt people.
- Mistaken Identity:
- The non-Winston Ghostbusters initially mistake the tentacled monster for Slimer, since he was raiding the fridge, which Slimer usually does.
- Peter initially mistakes Undead Peter for Winston, since he thought he was at home.
- Mythology Gag: Slimer is called "spud", which references Ray's movie line about him being "an ugly little spud".
- Not Me This Time: Slimer is the one who usually raids the fridge, which is why Peter, Ray, and Egon think it's him, but it's instead a tentacled monster.
- Not So Stoic: Egon screams when being caught by the Peoplebusters.
- Not Where They Thought: When the non-Winston Ghostbusters arrive in the other world, they initially think they're still in New York.
- Ocular Gushers: Slimer cries with the tears spurting out when the non-Winston Ghostbusters are gone.
- Oh, Crap!:
- Upon seeing that the Peoplebusters are on his and the others' trail, Peter nervously says, "Run! Or fly, or whatever it is we do now!".
- When Ray realises the Peoplebusters have followed them into the prison, he says, "Uh-oh, we've got company!".
- Oh, My Gods!: One ghost says, "Oh my ectoplasm!".
- Platonic Kissing: Slimer kisses Peter at the end.
- The Pratfall: Played for Horror — Peter falls backwards onto his butt in surprise and fear upon seeing an undead version of himself.
- Pun: Undead Egon, upon noticing his living counterpart, plus those of Peter and Ray, says, "We've got three live ones!".
- Red Eyes, Take Warning: The Peoplebusters, plus Undead Janine, have red eyes.
- Rhetorical Question Blunder: Janine complains, "Where's Egon when you need him!?" when the communication technology doesn't work. Winston replies, "That's what we're trying to find out".
- Say My Name:
- Ray and Slimer yell, "EGON!" when he starts getting pulled into the anomaly.
- Peter says, "Egon!" when he falls through the wall.
- Egon yells, "Peter!" when he's being caught.
- Shout-Out: Peter refers to the flying around and hiding that he and Egon have been doing as "playing Peter Pan".
- Speak in Unison: When Peter, Ray, and Egon find out that the undead guys are called the "Peoplebusters", they echo the name back in unison.
