In the Atlantic Ocean, an island appears out of nowhere, and so do two demons named Ashnar and Kishnar. They start fighting, but it ends in a stalemate since both are immortal. Ashnar suggests they get mortals to do the fighting for them. Meanwhile, Ray has a new boat and wants to take the other Ghostbusters, plus Slimer, on a ride. They agree (though Winston is reluctant because he gets seasick) but Peter wants to get back soon as he plans to ask a phone operator out.
They go sailing on Ray's small, motor-less sailboat called the S S Polliwog, but three hours later, they find there is no wind. Then, there is wind, but it's too strong, and sends the Polliwog crashing on the demons' island. Egon tries to build an SOS, but Winston thinks they should just leave, and Ray and Peter argue over how to build the shelter. Ashnar and Kishnar then decide to possess Ray and Peter, gaining strength from their "negative energy" and allowing the fight to happen. Peter then goes swimming in a pond and is possessed by Ashnar, while Ray is possessed by Kishnar while looking for sticks.
At base camp, Winston and Slimer are almost done building the hut, then Peter and Ray again start to argue, which causes them to morph into the demons. Slimer tells Egon, who falls through the roof, startling Peter and Ray, who return to normal. While everyone gathers food, Winston and Slimer tell Egon what happened. Then, they talk around a fire, but when Ray accidentally gets an ember on Peter, they argue again. This causes them to change again, but this time into bigger demons, but they don't remember it when they change back.
Egon looks up the demons, and finds out they're Sumerian and that Ashnar controls fire and earth, while Kishnar controls air and water. He then adds that they fight every thousand years, but can't win since they're immortal. He decides that they should keep Peter and Ray happy until morning, so they try to do so by singing, but it doesn't work and Peter and Ray argue and turn into demons a third time. As Ashnar and Kishnar fight again, Egon and Winston make a blaster that Slimer powers with the heat of some lava. Winston tries to shoot at the demons, but misses, and they chase the guys. However, when the sun rises, the demons disappear, Peter and Ray return to normal, and the island sinks. The guys sail back home, using their clothes (except their underwear) as a makeshift sail.
This episode provides examples of
- Arbitrary Skepticism: Egon at first doesn't believe Slimer when he says Peter and Ray turn into monsters, despite knowing full well that demons exist.
- Badass in Distress: Peter and Ray run the risk of being killed by Ashnar and Kishnar.
- Be Careful What You Wish For: The Ghostbusters and Slimer wish there was more wind, only to be caught in a storm.
- Blowing a Raspberry: Slimer blows a raspberry at Winston for calling him and Peter "unusual creatures".
- Blow You Away: Kishnar has wind-themed powers.
- Brick Joke: At the beginning, Peter sees a liner full of women in bikinis and, being Peter, wishes he was on there instead of the Polliwog. Later on, the same liner appears with the same women, still in bikinis, distracting him from his and Ray's latest argument.
- Chekhov's Volcano: Exploited — the volcano on the island erupts, and so Slimer holds the antenna for the machine in the lava flow to make it work.
- Comedic Underwear Exposure: At the end, the guys have to sail home in their undies, due to using their clothes as a sail.
- Death Glare: Peter and Ray give each other the stink eye during their arguments.
- Distressed Dude: Peter and Ray end up possessed, and in danger of being killed, by demons.
- Dramatic Irony:
- The Ghostbusters and Slimer don't realise initially that the island was made by demons, when we the viewers have seen it get made.
- While Slimer and Winston find out that Peter and Ray are possessed at the same time as the audience, it takes Egon a while to realise.
- Evil Laugh: The demons, especially Kishnar, do a lot of evil chuckling.
- Fear Is the Appropriate Response: When Ashnar and Kishnar chase Egon, Winston, and Slimer, Egon says his "plan" is to run.
- Fingore: Slimer accidentally hammers Winston's thumb.
- Glowing Eyes of Doom: Both Ashnar's and Kishnar's eyes glow.
- Goofy Print Underwear: When the guys are in their underwear at the end, Peter wears boxers with polka dots, while Ray wears boxers with Ghostbusters logos on.
- The Hyena: Kishnar does a lot of evil laughs.
- Immortality: Played for Lightmare Fuel — Ashnar and Kishnar want to fight to the death, but can't because neither can be killed.
- Instantly Proven Wrong: Ray says there's no land, only to encounter the island. Lampshaded when Peter points out that Ray said it.
- Lightmare Fuel: Two men are possessed by demons who drive strength from anger... which is bad news, since said two men argue like schoolboys.
- Making a Splash: Kishnar can control water.
- Mythology Gag: Ray calls Slimer a "spud" like in the movie.
- Narrative Shapeshifting: Slimer morphs into a monster when explaining that it happened to Peter and Ray.
- Not So Stoic: Egon yells when falling through the roof.
- Nursery Rhyme: One song that Peter and Ray's friends sing is "Row, Row, Row Your Boat".
- Oh, Crap!:
- Ray gapes upon seeing that the Polliwog has crashed.
- Slimer says nervously, "Oh no!" upon seeing Peter and Ray morph.
- Platonic Kissing: At the end, Slimer kisses Peter and Ray, happy that they're back to normal.
- Playing with Fire: Ashnar has fire powers.
- Pun:
- When Ray says sailing "brings out the best in a man", Winston retorts that it "brings out the lunch in this man!".
- Upon noticing the boat is called the Polliwog, Peter asks why they can't wait until it turns into a frog to sail on it.
- He then says he's made a "connection" with his crush — a phone operator.
- Pun-Based Title: The title puns on "beast" and "best".
- Red Eyes, Take Warning: Ashnar has red eyes.
- Shout-Out:
- Peter calls Ray, "Captain Ahab".
- Later, he calls him "Captain Queeg", who's a character from The Caine Mutiny.
- He then calls Winston "Mary Ann", who's a character from Gilligan's Island.
- Two of the songs the Ghostbusters and Slimer sing are "Home on the Range" and "The Fountain in the Park".
- Winston mentions he feels like The Flintstones.
- Skewed Priorities: Peter is more concerned about missing his date than about being marooned.
- Slapstick: Egon falls through the roof of the hut.
- Terms of Endangerment: Peter calls Ray "pal" as an insult.
- Transformation of the Possessed: Played with — most of the time, Peter and Ray look normal when possessed by Ashnar and Kishnar, but they take their forms when they get angry.
- Theme Music Power-Up: The theme tune plays during the fight scene.
- This Is Gonna Suck: Slimer makes a scared noise when having to fly near the lava.
- Underwear Swimsuit: Peter swims in a pond in his underwear.
- Water Is Blue: Kishnar, a water demon, is blue.
- You Wouldn't Like Me When I'm Angry!: Invoked — Ashnar and Kishnar deliberately possess Peter and Ray and make it so they'll take their forms when angry.
