Flanders' Ladder

"Flanders' Ladder" is the season finale and 21st episode of season 29. It aired on May 20, 2018. The episode was dedicated to the memory of Tom Wolfe, who died on May 14, aged 87.

Plot
On a stormy night, Bart tricks Lisa into playing and posts a photo of her surrounded by his dirty clothes on the Internet. At the dinner table, the internet line gets hit by lighting, cutting the family off it.

To pass time, the family digs up their old VHS, but when the VHS player breakes, Bart and Homer go to Ned's house to steal his router. Bart climbs the ladder to the attic, but gets hit by lighting, while another one hits the line bringing it back on. At Springfield General Hospital, Bart is in coma and Lisa gets revenge on him by giving him nightmares.

She makes him wake up in his bed, and has the ghost of Maude Flanders show up to scare him. Next, she sends in Milhouse while he decorates the treehouse with crosses to keep ghosts out, thought that doesn't work as the ghost of Maude comes back, but Bart manages to scare her off with Homer's socks.

Milhouse suggest him talking to his psychiatrist Samuel Elkins, about talking to a ghost. Turns out he's a ghost too, and Bart helps move on to the afterlife, and more ghosts appear. He starts helping the ghosts, though Lisa is causing him to get worse and worse and then Homer gets back from Krusty Burger, telling Homer he's dead from walking that far.

Due to this, Bart finally agrees on helping Maude, and she wanted revenge on Homer and the bullies kills him by throwing shirts to him. To avoid him going to Heaven, thus dying himself, he shoots the shirt to the Heaven light. Bart wakes up and starts telling Lisa he discovered how everyone is going to die.

Smithers dies at 50, by jumping into the Power Plant cooling towers. Smoke comes out of them with a heart that then separates in two. Homer dies at 59 by getting killed by police after exiting a food bank with a sandwich, and Wiggum dies at 62 when he was arresting him. Marge dies at 84, peacefully next to Ned, and he appends a picture of her on the wall full of memories of his many dead wifes.

Bart explodes fireworks in Skinner's direction, saying "Skinner sucks". Skinner dies at 119 after that, running over Bart in the process in his wheelchair, which dies at 80. Lisa dies at 98, realizing her meditation was all a waste of time. Ralph dies at 120 as a king, killed by his son. Maggie becomes a constellation and never dies.