InThe Name of the Grandfather is the fourteenth episode of Season 20.
The Simpsons travel to Ireland so that Grandpa can have a final drink at O'Flanagan's Pub, his old favorite watering hole. But when the small town of Dunkilderry isn't quite how Grampa remembers it and O'Flanagans has become a rundown, empty pub, he and Homer choose to buy it and make some repairs to the bar.
The Simpson family purchase a hot tub as a means to relax. In doing so, they forget to visit Abe at a family event. Homer agrees to make up for it and plans to do something Abe wants to do. Abe reminisces about a pub in Dunkilderry, Ireland called O'Flanagan's, where he claims to have had the best night of his life many years earlier. Homer chooses to take Abe there, but when the family arrive they realize Ireland has become a commercialized, hi-tech country of consumers and workaholics. The pub itself has run out of business as many of the patrons are now yuppies and have absolutely no interest in drinking. Homer and Abe sit down at the pub and start drinking while Marge and the kids tour various Irish landmarks. They visit the Giant's Causeway, Blarney Castle, the Guinness brewery and the city of Dublin.
After a long night of drinking, Homer and Abe awaken to realize they have bought the pub from owner Tom O'Flanagan. They rename the bar but get no business because pubs are no longer popular. Homer gets help from Moe, who suggests that they allow people to do illegal activities in their pub. They find out that smoking is illegal in Irish pubs and Moe urges the Simpsons to turn it into a smoke-easy. They do a roaring trade, but are closed down by the Irish authorities. As a punishment, Homer and Abe are deported back to the United States with a small fine.
In this episode, Marge, Lisa, Bart and Maggie visit the Giant's Causeway, Guinness Brewery and the Blarney Stone in one day. This is improbable, but not impossible, because the Giant's Causeway is in County Antrim in Northern Ireland, the Brewery which is in County Dublin and the Blarney Stone which is in County Cork.
Irish Nelson makes an appearance, carving his initials into Bart's butt when Bart's plan to trick unsuspecting people into kissing his butt (instead of the Blarney Stone) backfires.
In this episode, people actually immigrate to Ireland and get Irish sounding surnames!
The title of the episode is in reference to the Irish film "In the name of the Father."