Cynthia Crawford (the reporter first seen in "When Halloween was Forever") arrives at the firehouse to interview Peter. Janine initially doesn't let Cynthia upstairs, but does after an explosion happens. Upstairs, the Ghostbusters are working on a machine, and Peter takes Cynthia to his office. There, she notices Slimer and asks why the Ghostbusters have a pet ghost despite being ghost hunters, so Peter decides to tell the story of how Slimer became the pet.
The story begins just after the battle with Gozer. The firehouse and containment unit had been destroyed, so they planned to rebuild them. Their original uniforms had also absorbed spectral energy, necessitating the change to the ones they wear now. After the rebuilding was done, Peter was asked to burn the original uniforms, but he procrastinated and later forgot, and then they began to absorb even more spectral energy that was leaking out of an unseen crack in the containment unit.
At dinner, still in the past, Slimer appears and steals the Ghostbusters' food. They chase him, but he escapes and sticks around. They wonder why he is sticking around, with Janine suggesting he was lonely. Over the next few days, Egon wants to keep Slimer around as a test subject and Ray and Winston as a pet, but Peter is still salty about being "slimed" by him at the Sedgewick.
One night, spectral doppelgangers of the Ghostbusters appear in the old jumpsuits, wearing spectral versions of the proton packs that shoot ectoplasmic energy. They wake up the actual Ghostbusters, who fight back, and while they don't manage to trap the spectral Ghostbusters, they manage to repel them.
Several days later, the spectral Ghostbusters attack the actual Ghostbusters on an unrelated call. Back at the firehouse, the Ghostbusters determine that their doppelgangers want to replace them. Egon comes up with two solutions: either disarm the spectral Ghostbusters or make them run out of energy. The spectral Ghostbusters then enter and steal Ecto-1, which contains the proton packs. Peter runs to get a spare one lying on the floor, while the rest distract the spectral Ghostbusters, but Peter discovers the proton pack has only half a charge.
As Peter fights with the spectral Ghostbusters, Egon notices that using their weapons weakens them since they run on their own energy, and asserts that they can be trapped if they're weakened enough. He asks someone to distract them, and Slimer volunteers. One of the spectral Ghostbusters shoots Slimer, so Peter shoots back, launching the spectral Ghostbusters out of the firehouse. The genuine Ghostbusters retrieve their proton packs and trap the spectral Ghostbusters, and Peter finally agrees to let the others keep Slimer.
Back in the present, Cynthia thanks Peter and later makes a news report focusing on Slimer. Peter is at first jealous that she's prioritising Slimer over him, but then brushes it off.
This episode provides examples of
- Batman Gambit: During the first attack in the firehouse, Egon's doppelganger deliberately takes aim at Janine so that Egon will step out from cover. Egon only narrowly manages to push her to safety and avoid getting shot himself.
- Big Word Shout: Ambushed while in bed, Ray tries to reason with the spectral doppelgangers. Winston pushes him to safety while shouting, "MOVE!"
- Blowing a Raspberry: One of Slimer's ways of distracting the spectral Ghostbusters is to blow a raspberry at them.
- Bullying a Dragon: Peter mocks his spectral doppelganger, who then shoots at him, prompting the real Peter to note that was a bad idea.
- Call-Forward: In the ruins of the firehouse, Egon immediately suggests making the new Containment Unit larger than the old one.
- Continuation: The flashback details events following the movie, filling in the gaps on how Slimer became the Ghostbusters' friend, how they ended up having different uniforms, and why their containment unit is bigger.
- Continuity Snarl: Egon muses that rather than escape with the other ghosts when the containment unit exploded, Slimer remained in the firehouse. This contradicts the film where Slimer was seen in the montage of the freed ghosts running amok, with him eating all the franks at a hotdog stand. That said, he likely could've followed the Ghostbusters back to the firehouse following their victory over Gozer.
- Creating Life Is Unforeseen: Peter accidentally creates the spectral Ghostbusters by leaving the old uniforms near the containment unit, causing them to collect spectral energy.
- Creepy Monotone: On the rare occasions the spectral Ghostbusters talk, it's in this fashion.
- Dramatic Irony:
- Peter initially doesn't realise he was the one who led to the creation of the spectral Ghostbusters, when the viewers know all along.
- The Ghostbusters find out Slimer is around after the audience does.
- Fingore: Winston gets an electric shock on his finger when he touches the machine and then sucks on his finger.
- Foregone Conclusion: Peter initially doesn't want Slimer around, but because it's in the past, we know that he ends up staying.
- Hard-Work Montage: How the firehouse goes from a ruined mess to a pristine living environment.
- Hidden Heart of Gold: When Peter agrees to let Slimer stay, he insist that no one tell anyone he said so. Cutting back to the present, he tap dances around how he agreed to let Slimer stay.
- Hurricane of Euphemisms: Peter describes having a pet ghost as a Ghostbuster as "strange", "weird", "unusual", and "sick".
- Hypocritical Heartwarming: Peter constantly grouses about Slimer throughout the flashbacks, but he's outraged when the doppelgangers manage to blast the spud.Peter: You zapped my little buddy! [opens fire]
- I Just Want to Have Friends: After Egon questions why Slimer stayed in the area rather than flee with the other ghosts, Janine suggests the spud is lonely and responding to the only people that ever paid attention to him. The guys brush this off, but Slimer spends the next few days awkwardly trying to approach and befriend them.
- Insane Troll Logic: When Egon is asking Peter to check if certain machines are working, with Peter replying, "Check", Egon tests if he's still paying attention by asking, "Transwarp drive?". Peter still replies, "Check", then when Egon says they don't have a transwarp drive, Peter rationalises that if they don't have one, it can't malfunction.
- Irony: Lampshaded by Cynthia, who notes that it's strange that the Ghostbusters have a pet ghost.
- Kill and Replace: The spectral Ghostbusters' intention is to eliminate their living counterparts and assume their lives.
- Meaningful Name: Ray gives Slimer his name solely because it would annoy Peter.
- Mirthless Laughter: Peter chuckles awkwardly upon realising that he was the one who led to the spectral Ghostbusters' creation.
- Mistaken Identity: When the spectral Ray taps the real Ray awake, he initially thinks it's Peter doing it.
- Not Listening to Me, Are You?: Egon tests if Peter is paying attention by having him check if the "transwarp drive" (which they don't have) is malfunctioning.
- Oh, Crap!: Ray's eyes widen in fear when he first sees the spectral Ghostbusters.
- On Three: Egon tells the others to shoot at the spectral Ghostbusters on the count of three.
- Platonic Kissing: Slimer kisses Ray when he doesn't want him to endanger himself.
- Puppy-Dog Eyes: Slimer gives Peter a wide-eyed look when begging him to let him stay.
- Screw This, I'm Outta Here:
- With the first attack in the firehouse not going their way, the spectral Ghostbusters beat their feet out of the building.
- When the spectral Ghostbusters return during a job and have the advantage, Peter uses Ecto-1 to get the others to safety.
- Self-Deprecation: Cynthia politely says it's a bit strange for a ghost to be living with Ghostbusters. Peter says it's outright weird, eccentric, and sick.
- Shout-Out: Egon checks if Peter has his attention by asking about the "transwarp drive", which they don't have. A "transwarp drive" is something from Star Trek.
- Sickly Green Glow: The spectral Ghostbusters are lime green and glow in the dark.
- Silent Treatment: Egon threatens to stop talking to Peter for a week when he's frustrated with him clowning around instead of doing the repairs properly.
- Tempting Fate: Peter balks at his spectral counterpart using his name.Peter: There's only room in this town for one Peter Venkman!
Spectral!Peter: I agree, so one of us must go. [opens fire]
Peter: [dodging] Why do I say stuff like that?! I always get in trouble! - This Is Gonna Suck: Peter comments in a resigned way that things are looking bad when the spectral Ghostbusters show up at the firehouse.
- Title Drop: The Ghostbusters tell their spectral doubles that "the real Ghostbusters are here to stay!".
- Unreliable Narrator: After the guys figure out how this problem happened and glare at Peter, his narration insists they all agreed it was no one's fault.
- Unwitting Instigator of Doom: Peter accidentally leads to the spectral Ghostbusters' creation by procrastinating burning the uniforms, leaving them by the containment unit, and then forgetting about them.
- Whole Episode Flashback: The episode tells the story of how the Ghostbusters got Slimer.
- Women Are Wiser: Janine correctly observes that Slimer is lonely and wants some friends.
