Homer puts Lisa's college fund into online banking as a way to fight back against big banks. Lisa becomes a gambler and soon rises her college fund with the help of Jennifer Tilly. Meanwhile, Grampa Simpson mysteriously disappears from the Springfield Retirement Castle, and leaves behind clues to parts of his life that the family never knew before, like the time he was married to a black singer named Rita LaFleur and when he owned a restaurant with Marvin Hamlisch.
Homer goes to Gulp 'N' Blow for onion rings.However, due to being stressed by a female waitress, a man complaining about a homeless man who had finished a shower in the bathroom sink, and Milhouse's karate's team, the cashier accidentally throws hot onion rings at Homer's face. Homer sues Gulp 'N' Blow and becomes entitled to a $5,000 due to legal fees and ends up being talked into putting the money into a college fund for Lisa on a poker site. Marge then remembers and reminds Homer that they were supposed to visit Grandpa on the day of the trial. Homer and Marge go to the retiriment home and learn that Grandpa is missing. They look for Grandpa's belongings to see if they will help for Marge to find that says "Spiros. The place that changed my life...' so they decide to see if Grandpa is at Spiros.
Homer and Marge go to Spiros to be told by the owner that Abe was a busboy and he fired him after Abe didn't clean expired bread due to Abe being distracted by a singer named Rita. Marge decides to call Rita who invites them to her house and she reveals that she is Abe's wife.. She reveals that after she and Grandpa were fired, they become partners in singing. Abe then proposed to her, and when they were married a six-year-old Homer tied his foot to the car and ended up in the hospital. Rita is then called for a European singing tour but due to Homer, Grandpa stays with Homer and bids Rita goodbye at the airport and never sees her again.
Rita then gives Homer an old cologne of Grandpa which gives Homer and Marge the idea of finding Grandpa at the store the cologne came from. They find Abe there and apologize to him about how they found him as boring. They go home for Grandpa to find Rita in the house playing they're song and joins her, reconciling their marriage.
Meanwhile, after Homer puts Lisa's college fund on the poker site, Lisa finds Bart playing with her college money. After she stops Bart from playing, she plays poker. After watching a video of Jennifer Tilly giving instructions of poker, she plays and wins up to $413,762. She then goes all in, but loses to Sideshow Bob. She bitterly weeps until Bart reveals that he is Sideshow Bob but due to him and Lisa being under age 18, he and Lisa have gone back to the original $5,000. Bart then reveals that he did it due to feeling bad for Lisa and she reveals that he recorded him for her memoir.