Roger and Anita are heading out on a picnic with Lucky, Cadpig, Rolly, and Spot. Rolly insists that they just have the food right away. Lucky reminds him that they cannot eat before they find a spot, with Cadpig also trying to explain how picnics are more than just food. Spot then notices some fog which Roger and Anita walk into, and the Dalmatians follow them.
Inside the fog, they find a town called DeVil Ville. Roger figures that Cruella is behind this. However, Anita points out that they are only half a mile from home, and even Cruella's millions couldn't build this town in one night. Lucky is eager to investigate and rushes in, with the others chasing after him.
The town itself seems to be a colonial period town. Roger and Anita seem to instantly fall in love with it, while Rolly is invited to try the butcher's meats. It is at this point when an ominous man arrives in a carriage. The man appears to be a ruthless mayor whom Spot seems to recognize. Lucky seems more fixated on the carriage hound named Rebecca and follows after her, whereas Cadpig thinks the town is a pro-environmental commune and goes to explore the town.
The mayor then sees Spot and chases her from the town, due to having a hatred of chickens, and Spot realizes where she has seen him before.
Spot goes to Villa DeVil and finds the mayor's portrait in the gallery, which reads: "Judge Dimsdale De Vil, born in 1631." This terrifies Spot, thinking he must be some ghost (and worse, related to Cruella) and heads back to the town to the warn the others.
As she does, however, Scorch (who Cruella is taking for a walk in her golf course) notices Spot and chases after her, pulling Cruella with him. When Cruella arrives in DeVil Ville, she is angered that someone used her name without permission and searches for whoever is in charge to sue them.
Back in DeVil Ville, Lucky is getting to know Rebecca, but strangely cannot recall what television is. Rolly is still eating at the butchers, whereas Roger and Anita are so entranced that they do not want to leave.
Cruella then runs into Judge Dimsdale DeVil, who recognizes Cruella to be a De Vil too. He explains many centuries ago, he started off as the tax collector of the town, but was so ruthless and iron fisted that he rose to become judge and lord mayor of the town. This was interrupted, however, when Hester Hen, the town witch, realized that Judge Dimsdale DeVil will not stop until he owns the whole world, and since no one had the backbone to stop him, she felt that the task would fall onto her and Katrina, her chicken.
To keep the world safe from "The evil De Vil," Hester Hen placed a curse on the town that appears only for one day every hundred years and shall vanish from the face of the Earth. While under this spell, all the inhabitants of the town are to be mindlessly happy, to make Judge Dimsdale De Vil more miserable by comparison, and, under the risk of death, "The Evil Devil" is bound within the town's border to spend eternity in this prison of his own making. Upon Katrina's suggestion, the spell does not affect chickens.
Hearing this, Cruella realizes that if she can have this town so that the Dearlys are still in DeVil Ville, when it vanishes again, she'll be able to get the Dearly Farm.
Spot overhears this and finds Cadpig and Rolly. She tries to snap them out of Hester Hen's spell before eventually trying the fairy tale approach and kisses them. This snaps Cadpig and Rolly out of their trance (who both become disgusted from Spot's kisses), and they are now disturbed by the town. The two pups and Spot then head off to find Lucky.
Judge Dimsdale DeVil takes Roger and Anita on a tour of the town before locking them in the town jail. When Cruella tries to thank the Judge, he then locks her in the stocks. He explains that when Hester Hen said "The evil De Vil" was bound in to the town, she never specified which evil De Vil, so he plans to have Cruella take his place in the town. He heads off to collect his gold before heading to the town's border.
Spot is able to get Lucky out of the curse (who also becomes disgusted after Spot kisses him), as well as Rebecca, who now realizes what a cruel man that Judge Dimsdale De Vil is. She then offers to help the Dalmatians by showing them the way to the town jail. Upon arriving at the jail, they free Roger, Anita, and Cruella and run off to the town's border, but not before Spot kisses Roger and Anita (who become disgusted as well) to break the spell on them.
Cruella spots Judge Dimsdale De Vil and tackles him for his betrayal. She then realizes that the sun is setting and tries to escape, but Judge Dimsdale De Vil pulls her back. Roger and Anita attempt to help Cruella.
Lucky asks Rebecca to come with him, but she decides to stay in DeVil Ville to keep Judge Dimsdale De Vil in check, like how Lucky does with Cruella.
Realizing that Roger, Anita, and Cruella are losing ground (and that they will be trapped in that town until at least 2098), Spot charges in and takes down Judge Dimsdale de Vil, allowing the Dalmatians, the Dearlys and Cruella to escape. When the town disappears, though, they cannot remember anything about it. Spot is okay as well, since she is immune to the curse and therefore didn't vanish with DeVil Ville.
The Dalmatians question Spot what she's talking about. Spot guesses that if she kisses them again, it may give them their memories back. She then starts chasing the now-terrified pups to kiss them.
- The episode has similar story elements to the show Brigadoon, about a town that appears for one day every hundred years, though the reasons as to why are different in the episode. The show also has a modern man enamored with one of the females of the town, similar to Lucky and Rebecca in this episode. This also led to fans pairing the two Dalmatian pups together.
- Hester Hen, the witch who places the curse on DeVil Ville, is voiced by Alice Ghostley, most likely as an homage to her role in Bewitched.
- Hester Hen also bears a strong resemblance to Nanny, indicating that she could be her ancestor.
- Judge Dimsdale De Vil is voiced by Efrem Zimbalist, Jr., known for his roles in 77 Sunset Strip and The F.B.I., along with the voice of Alfred Pennyworth in the Batman animated series.
- Among the occupations that Judge Dimsdale De Vil gained were: sheriff, notary public, judge, bail bondsman, birthday clown, dog catcher, comedy driving, school, and Lord Mayor.
- Portraits of Malevola De Vil, Ivy De Vil, P.H. De Vil, and Cecil B. De Vil can be seen in the DeVil family gallery as Spot checks where she saw Judge Dimsdale De Vil before.
- Although Cruella is a DeVil (one of those unaffected by the curse), after the town vanishes, she does not remember a thing about the curse, but Spot, being a chicken who is not affected, does. Though it is possible that only the "mindlessly happy" part of the curse doesn't apply to the DeVils.