The Ghostbusters are chasing a poltergeist, which Egon determines must be getting its energy from a source. They find a whole lot of trash cans with monsters in them, and the monsters then combine to form the poltergeist. The poltergeist creates wind that blows the Ghostbusters around, then escapes, and Egon and Ray determine it was getting its energy from smaller ghosts.
When they get home, everyone else throws Winston a surprise party because it's his birthday. Janine brings him a large, fancy cake, but Slimer eats the whole thing before Winston can even blow out his candles. Peter scolds Slimer, but the rest of them, even Winston himself, take it in stride.
That night, Slimer is sad about Peter's scolding, so he writes a note and flies away. Janine sees the letter and shows the guys. Ray, Egon, and Winston are keen to start searching, but Peter is still salty. Meanwhile, Slimer, remembering Peter berating him for being a Big Eater, changes his mind about eating some candy, then spots a group of ghosts and chases them.
Peter goes out in the rain, transparently lying that he's not going to look for Slimer. Egon realises that Slimer is in danger, since poltergeists feed off the energy from ghosts, and if they steal Slimer's energy, they could make him powerful and evil. Slimer catches up with the other ghosts, who are at a table with the poltergeist.
While Egon and Winston search for Slimer, Ray tries to find him by not searching, when a woman shows up who he recognises as his second-grade teacher. While the poltergeist goes out to cause chaos, Peter finds Slimer, but Slimer doesn't go with him.
Peter tells the others that he's found Slimer and they pursue him to a building, where the poltergeist is starting to absorb the smaller ghosts. The guys break in, but the poltergeist has absorbed them all, including Slimer. Luckily, however, they shoot at the poltergeist and free Slimer. They try to trap the poltergeist, but he steals the proton packs, then starts shooting at them with laser vision. Then, he picks up all four of the Ghostbusters and pulls them towards himself. Slimer sees the proton packs and uses them to free the guys. He drops the proton pack while it is still discharging and Peter picks it up and aims it at the poltergeist. The rest of them join in and they manage to trap all the ghosts and the poltergeist.
They quickly go home and empty the trap before it overloads, then they throw Slimer a surprise party. Peter initially denies having ever missed Slimer, but when Slimer cries, he admits that he missed him a little.
This episode provides examples from
- Ate It All: Winston's cake was made for six people, and was big enough to have leftovers, but Slimer eats it all in one bite. He does it again at the end, but the Ghostbusters learned from the previous incident, and concealed a cake in the false bottom of the cake stand, so the rest of them could actually have some.
- Birthday Episode: Downplayed. While it doesn't take up too much of the plot, the episode's conflict starts with Slimer eating Winston's birthday cake.
- Blow You Away: The poltergeist can create wind.
- Covered in Gunge: Peter's attempt to hug Slimer leaves him covered in green slime.
- Cyclops: A few one-eyed ghosts are seen.
- Distressed Dude:
- Slimer ends up being absorbed by the poltergeist and in need of rescue.
- The poltergeist then picks up the Ghostbusters and pulls them towards himself.
- Ectoplasm:
- Slimer gets a bit of green gunk on Ray's cheek after kissing him.
- When he writes the goodbye letter, Slimer leaves a pool of green slime on Janine's desk.
- He then gets ectoplasm all over Peter when the latter tries to hug him.
- Evil Laugh: The poltergeist laughs evilly several times.
- Hesitation Equals Dishonesty: Peter leaves the firehouse, claiming that he's going on a walk and pausing a lot. Janine points out that it's weird for him to wear his Ghostbuster outfit just to go for a walk, and clearly suspects that he's actually going to look for Slimer.
- Horrifying the Horror: Played for Laughs; while Egon is looking for Slimer, he's followed by a street tough who asks him what he's looking for. Egon, oblivious to the threat, gives an answer which naturally sounds completely off the wall. When said tough's gang asks him why he didn't let them jump Egon, he says that his father told him he shouldn't mess with someone who's stranger than he is.
- The Hyena: The poltergeist is prone to evil laughter and the smaller ghosts whose energy he feeds on often laugh shrilly.
- Jerkass Has a Point: Although Peter was somewhat over-harsh when reprimanding Slimer, to the point that Slimer felt forced to leave home, he wasn't wrong to think that Slimer shouldn't get away with eating food that wasn't all meant for him, and that he needed to learn from his wrongdoing.
- Mythology Gag: Peter refuses to look for Slimer, saying, "I'm the guy he slimed!". Slimer "slimed" Peter in the movie.
- Our Ghosts Are Different: This episode reveals that ghosts produce "energy", that poltergeists feed off.
- Platonic Kissing: Slimer kisses Ray on the cheek at one point.
- Red Eyes, Take Warning: The poltergeist has red eyes.
- Russian Reversal: Upon seeing the trash monsters, Peter jokes, "Looks like the trash wants to take us out!".
- Shout-Out: When the poltergeist blows the Ghostbusters around, Peter says, "Didn't I see that in The Wizard of Oz?".
- Surprise Party:
- Around the beginning of the episode, Winston's friends throw him a surprise birthday party.
- Slimer's friends throw him a surprise party to welcome him home.
