"The Ziff Who Came to Dinner" is the fourteenth episode of Season 15.
Marge's old prom date Artie Ziff returns to Springfield, having lost his money and his Internet business, and asks to stay with the Simpsons until he gets back on his feet. What Artie doesn't tell them is that he is also a fugitive from justice, sought by the SEC for cheating his stockholders.
Homer takes Bart and Lisa to the movies, but he has to bring Ned Flanders' boys with him, because Ned has taken the senior citizens for ice cream to celebrate Jasper's birthday. However, at the Googolplex Theatre, every kid-friendly movie is sold out, and Rod and Todd will not let Homer see a raunchy comedy called "Teenage Sex Wager", since it is one of the many movies that is condemned by a Christian publication called What would Jesus view?. After listening to his friend, Lenny Leonard, mention that he had a small part in the horror movie, The Re-Deadening, as a gardener, Homer takes the kids to see the movie. The movie is very scary, causing it to scare Bart and Lisa at home, who think they hear noises from the attic. However, when they look in the attic, their fears scare them away. Later, when Bart and Lisa arrange to have Homer and Marge look in the attic, they discover Marge's old high school prom date, Artie Ziff, living there.
Artie Ziff explains that he was living in the attic because he ran an unsuccessful Internet business, Ziffcorp, and lost all of his money after spending it on many extravagant items, which then got repossessed (including the repo vans). He chose to live with the Simpsons because he claims that Marge was the closest thing he ever had to true love. Marge, however, quickly points out that she and Artie only had one date where he wasn't a much gentleman as he tried to force himself onto her and almost raped her on their high school prom night. Artie promises that he won't hit on Marge if he stays with them, which Marge objects to, but Homer, Bart, and Lisa do not. While living with the family, Artie connects with Lisa by reading The Corrections to her. He then tries to buy ice cream for Bart and Milhouse, but when Artie's credit card gets cut up, he attempts to hang himself (which does not work, as the noose is not on his neck tight enough to kill him, nor is Artie high up off the ground for a hanging to be physically possible). Homer gets Artie down and takes him to Moe's.
Marge sees on the news that the SEC is looking for Artie Ziff. Meanwhile, Artie is playing poker with Homer and his friends, and Homer wins 98% of Artie's company's outstanding stock. Suddenly, the SEC crash in the tavern to arrest Ziff, but Homer says that he owns 230 million shares of Ziffcorp, making him the majority stockholder. To protect himself, Artie has Homer take the blame, making Homer getting taken into SEC custody, and placed on trial.
While Homer is on trial (and naturally makes a fool of himself after failing to understand the Fifth Amendment), Marge blames Artie for Homer being put on trial and further adds to the situation that his self-centeredness is the main reason nobody likes him.
However, Homer gets convicted and given a ten year prison sentence. Marge, finally having enough with Artie, kicks Artie out of the house and tells him that she never wants to see him again. While visiting Moe's Tavern, Artie gets down-talked by Moe and everybody else who was at the poker game, who all hate him for getting Homer imprisoned. While there, he also encounters Patty and Selma, which she comes to take Artie to her apartment after he mentions putting Homer in prison. As they spend the night together, Artie makes a plan to turn over his corporate books in order to admit that he is the real crook. Ziff turns himself in, and Homer is released from the penitentiary. The family takes one last look at their "Uncle Artie", who is using a squirt bottle to douse the prisoners' cigarettes, much to their rage of fury.