"Bart of Darkness" is the first episode of Season 6. It aired on September 4, 1994. The episode was written by Dan McGrath and directed by Jim Reardon. The episode is an obvious parody of Alfred Hitchcock's movie Rear Window.
At the start of very hot summer vacation, the Simpsons' fridge breaks after a failed attempt to beat the heat. Fortunately, Otto comes to their salvation with the "Pool Mobile". Bart and Lisa and the rest of the neighborhood kids enjoy the pool time until Otto tells them that their time is up and that they don't have enough money in the budget to come back. Upon hearing this, Bart and Lisa convince Homer, rather easily, to buy them a pool. After mistakenly building a barn on the first try, the Simpsons build a proper pool and suddenly Bart and Lisa become the most popular kids in the neighborhood. All the kids at Springfield Elementary, as well as kids they don't know (and who also don't know them), show up at the Simpsons house every day to swim. However, when Bart is dared to jump from his treehouse into the pool, he gets distracted by Nelson ("Your epidermis is showing!") and falls and breaks his leg. Bart is forced to stay indoors with a cast on his leg while Lisa enjoys her newfound popularity with the other kids swimming in their pool. Marge and Lisa soon take notice that Bart is becoming isolated and weird. To suppress Bart's sudden paranoia, Lisa gives Bart her telescope for something to do. He first comes to the conclusion that the universe is boring and instead uses the telescope to spy on Springfield residents. He finds nothing even remotely interesting to spy on, until he hears a female scream and spots Ned Flanders burying something in his backyard.
After hearing a conversation between Ned and Rod and Todd, Bart thinks that Ned will kill them too. When Lisa becomes unpopular again when Martin Prince sets up a better pool in his backyard, Bart convinces Lisa to sneak into Flanders's house and snoop around for evidence. However, Bart sees Ned coming into his house with an axe. Certain that Ned intends to kill Lisa, Bart tries to call 911, but only gets an answer from an automated recording. Bart decides to save Lisa on his own and struggles to get down the stairs and out the door, encountering many setbacks on the way to Ned's house. Meanwhile, Lisa becomes aware that Ned has returned home and is carrying an axe. She hides in the attic and Ned follows her. Bart arrives just in time for Ned to put the axe on a mount on the wall. He is dumbfounded when he sees Bart, who demands to know why he killed his wife. Ned is shocked to hear Bart say that he murdered his wife and passes out.
The police arrive to the scene with both families, including Maude. Maude explains that she was actually at Bible camp for a week, learning how to be more judgmental. When Bart asks Ned about the "murder" that he saw, Ned breaks down and says that he accidentally overwatered Maude's favorite ficus plant, panicked, and then buried the remains; he had planned on replacing it before Maude got home. Bart then asks about the woman that he heard scream, and Ned says that he can't explain that. When Lou digs up Maude's dead ficus, Ned lets out a shrill-like scream. Bart then concludes that everything is normal.
Meanwhile at Martin's house, his pool becomes too overcrowded and bursts. Everyone leaves and Martin becomes unpopular again. Before the credits roll, Nelson snatches his bathing suit off.