Homer stands a blindfolded Marge, Bart, and Lisa at the top of the basement stairs. He announces that his big surprise is right in front of them. They all put one foot forward, and tumble down the steps. After they remove their blindfolds they realize that Homer remodeled the basement. Marge wonders how Homer could afford such a luxury, prompting Homer to reveal that he’s declared bankruptcy. In court Homer tells the judge that all of his assets are protected. The judge informs him that he’s quoting from the old bankruptcy law. Under the current law, Homer is required to pay his creditors everything. The judge appoints a financial officer to supervise the repayment of Homer’s debts. The accountant insists that Homer make some serious cutbacks; including the money spent to keep Grampa in a nursing home. Grampa moves into the Simpsons’ house, where he begins annoying Bart and Lisa. They make their way to the front stoop, where they notice Flanders receiving a large shipment of empty boxes. Flanders tells the kids they’re complimentary, as the company expects him to ship his left-handed wares using their service. Bart and Lisa are intrigued. They scheme to have a quantity of boxes delivered to the house. Meanwhile Grampa drives Homer and Marge crazy. They decide to have a night out by themselves. Marge invites Selma to the house to keep an eye on Grampa and the kids. Grampa and Selma discover they have a lot in common, including their passion for lemon candies and bingo. As the night wears on, they grow closer and closer, until Grampa leans in and gives Selma a kiss. At that moment Marge and Homer return home. They gasp at the sight of Grampa kissing Selma.

Homer tells Grampa he never wants to see him kissing Selma again. Grampa insists that Homer can’t tell him what to do. A deliveryman wheels a large stack of empty boxes into the backyard. Bart and Lisa accept the delivery, telling the man they run their own company. That night Grampa and Selma share a romantic dinner at a restaurant. As their romance deepens they frolic at the beach, where Homer continues to protest that it isn’t right for the two to be dating. While Homer walks down the street one day, Selma’s sister Patty calls out from the shadows. Patty tells Homer he’s not the only one who has a problem with the relationship. Bart and Lisa use the empty boxes to construct a magnificent box-fort that takes up most of the backyard. When the delivery man sees the fort he demands the return of the boxes, insisting they’re for shipping, not for the world of “pure imagination.” He says he’ll return later in the day to reclaim them. Homer meets up with Patty at a sporting-goods store. Patty disguises herself, making her look like Selma. Homer dons a moustache, hat, and cape, making him look like a dashing Latin lover. Knowing that Grampa will happen by in a few minutes, they make their way into a shopping mall, where they make out. Grampa falls for the ruse, and mistakes Patty for Selma. His lip begins to quiver. Suddenly the real Selma walks by. Grampa realizes Homer tried to trick him. He gets down on one knee, and proposes to Selma, who happily accepts. Homer is horrified.

Grampa and Selma marry at Springfield town hall. They make their way to their new starter house, where Selma says she’ll have to take a new supervisor job so she can afford the mortgage. While Selma is at work, Grampa cares for her baby, Ling. Selma begins to worry that Grampa might not be up to the challenge. A group of delivery trucks shows up at the Simpson house. Bart and Lisa decide to make their stand. The deliverymen launch an assault against the fort, wielding mail tubes like broadswords. Eventually the deliverymen are forced to retreat, but the victory celebration is short-lived: the fort comes to the attention of homeless people, and young couples looking to move into their starter homes. Bart and Lisa decide to dump the fort into Flanders’ backyard. Rod and Todd climb into the structure, but begin to scream when the two factions descend upon it. Selma begins to crack under the stress of her new job at the DMV, especially when two lines of customers begin to quarrel. She starts to hyperventilate. At the house Grampa gets befuddled in the kitchen, accidentally starting a fire when he microwaves a VHS tape. Back at the DMV Selma’s presentation to some hotshot DMV staffers does not go well. Moments later Grampa enters carrying a crying Ling. That night Selma realizes the marriage isn’t working out as they’d hoped. They decide to spend one last passionate night together.