Richard and Nicole are asleep in bed when Richard hears a low moaning sound coming from the attic. He assumes that it's a ghost and gets very scared, prompting Nicole to turn on a musical baby lamp which Richard finds very relaxing and falls asleep.
The next morning, Nicole finds Richard in the cupboard hiding from the ghost while getting another box of cereal for Gumball. Anais and Darwin question why he's pouring the cereal in his trousers and he leads them both up to the attic.
Gumball reveals that he has been keeping Mr. Robinson in the attic ever since he found him in the shed. For some reason, Mr. Robinson hasn't said a word or moved a muscle since he found him, so Gumball decides to give Mr. Robinson a comedy show starring himself. It doesn't work, and after a routine Mr. Robinson gets up and looks out the window to see his wife getting the mail. She glares at him and walks away muttering something angrily.
Obviously upset, Mr. Robinson begins to yell "WHY?!" to Richard's hot dog splatting on to the ceiling. Richard thinks the poltergeist ruined his sausage. Gumball shows him a picture of a cat playing a kazoo but this still has no effect on him. Gumball finds a box containing "Electro Fat", which is apparently an exercise aid that electrocutes you into getting into shape. He hooks up Mr. Robinson to the aid and turns it on, which causes him to be electrocuted. They crank the power up to its highest setting which shorts the house's electricity out.
Inside, Nicole accidentally triggers a trap that Richard had set for the ghost. The trap hangs her upside down while the power is still out, making Richard think that the ghost is making her levitate when the lights come back.
Gumball and Darwin are observing the severely electrocuted Mr. Robinson and compare him to a bulldog staring at the sun. Seeing Mr. Robinson sad reminds them of the last time they saw him happy, which was when Darwin's head was being squished in between the automatic doors of Food N' Stuff. Remembering this, they conclude that Mr. Robinson is more partial to physical comedy and not stand up.
Back in the house, Nicole is still hanging upside down. Richard begins to hysterically argue with Nicole about the ghost situation, causing Mr. Robinson to curiously peek at them. Feeling emotionally triggered by the sight of Nicole and Richard arguing, he explains that he lost his spark, which is his anger, forcing his wife to kick him out as he has a short flashback to all the times and places he and Margaret argued. Gumball figures out that what was missing in Mr. Robinson's life was his anger, which is what made the Robinsons love each other.
Gumball decides to lower Mr. Robinson down out of the window to get him outside without his parents noticing, the plan works, but Mr. Robinson still falls onto the Wattersons' lawn. Outside, Mr. Robinson sees his wife watering, and then beheading flowers. The boys encourage Mr. Robinson to have an argument with his wife, but he claims to not be that man anymore. Gumball and Darwin then attempt to use Mr. Robinson like a puppet and pretend to make him be angry, but Margaret sees through their trick, causing Mr. Robinson to get depressed again and start crying under the sheet.
Just then, Richard comes out of the house with the vacuum cleaner in hand and charges at Mr. Robinson, assuming that he's the ghost and was about to attack his sons. After Richard violently smashes him with the vacuum cleaner a couple of times, Gumball whacking him with a rake while protecting him from his dad, and Mrs. Robinson throws his suitcase on him, Mr. Robinson snaps with the pressure of the day's previous events and his anger returns.
In his fit of rage, he attempts to destroy The Wattersons' backyard but miserably fails. However, seeing her husband back to his old grouchy self reignites the spark in their marriage as Mr. Robinson throws open the gate and snuggles his wife lovingly. After rejecting Gumball and Darwins' proposal to be friends now, the Robinsons leave.
Richard is feeling insulted by Mr. Robinson, who called his house, lawn chairs, and his clip-on tie ugly and tacky, so Gumball shows him a strange picture of a cross-eyed gopher lifting a dumbbell. This somehow cheers him up as he states that even though the Robinsons have nicer stuff than he does, he knows how to treat his wife. Contrarily, Nicole is seen alone in the house, biting through the ropes. She manages to free herself but is again caught in another trap, she yells to Richard angrily and the episode ends.
Due to the fact that in some countries there is no translation for Poltergeist, in some countries the episode received an adaptation, and the title is translated to "The Ghost", thus making this the only episode to have re-used name.
This episode marks the second time that Mr. Robinson has a major role. The first time was in "The Debt."
This episode appears to take place after "The Car," as Richard's Electro Fat is stored away in the attic.
For some reason, the window on the roof in front of the house is a part of the attic instead of Gumball and Darwin's room as it was in previous episodes.
Mrs. Robinson was seen with a genuine smile in this episode, which is the first time this has happened.
All of Gumball's six whiskers can be seen for the third time, after "The Pressure" and "The Ghost." They can be seen when Gumball impersonates a pea on a fork.
Richard wearing the vacuum cleaner on his back is a reference to the proton packs from the movie Ghostbusters. It could also be a reference to Luigi's Mansion, in which Luigi must defeat ghosts with a special vacuum called the Poltergust 3000.
When Mr. Robinson was remembering everything that happened to him, he cracked the lenses on his glasses. But when he said, "Your tacky lifestyle!", his glasses' lenses weren't cracked.
When Mrs. Robinson shut the mailbox, the lid didn't move.
When Nicole was hung upside down, her skirt was not affected by the gravity.
At the the start of the episode Gumball put the cereal "Daisy Flakes" down his pants but they were never seen nor mentioned for the rest of the episode.
In Darwin's flashback, the white circles of his shoes are missing. Also, in the same scene there's a reflection of a disabled sign in the glass but it is facing towards the mall, not the parking lot.
Despite the fact that Nicole says that there are no such things as ghosts, Carrie is one.
This could be because she hasn't met Carrie yet.
When Darwin is being pushed by the electric doors, the reflections on the doors stay on them despite the fact that the doors are moving.
When Nicole says "Richard, by all means, be hysterical. But don't forget to breathe!" her sleeves are missing.
When Mr. Robinson looked out of the window in the attic, it is revealed that the uppermost window of the house as viewed in the outside is for the attic window, as opposed to the episode "The Responsible" where the window was for Darwin and Gumball's room.