Grandpa's about to turn 81 years old, and he figures that since no one in his family has lived past 81, he's going to die soon. Arnold takes him to Dr. Steiglitz (the first doctor Phil's seen in over twenty years) who's amazed that Phil's so healthy for his age, and states that Phil could easily live another 70 years, possibly more. Phil, however, ignores this and still thinks he's going to die. So Arnold and Grandpa spend time together after Gerald tells him to do.
Grandpa, Grandma, Arnold and the boarders are sitting down to breakfast. Grandpa is in a bad mood, spurred on by the bickering of the boarders. Arnold inquires about Grandpa's bad mood, and discovers that Grandpa will soon turn 81, and he believes that the men in his bloodline are cursed to die at 81-years-old, citing his father, grandfather and great-grandfather. Arnold accompanies him on a check-up with his doctor, who claims that Phil is in spectacular condition for a man of his age. Grandpa, however, refuses to accept his diagnosis.
Grandpa goes about leaving his family and boarders his possessions. To Arnold he gives the Packard, and Grandma the boarding house. Arnold explains his tough situation to Gerald, who suggests inspiring Grandpa by taking him out to do his favorite things. Grandpa and Arnold go to the movies (at The Kiska, specifically), ice skating, a baseball game and enjoy corn dogs down at the docks. After all of his efforts, Arnold still hasn't managed to convince Grandpa that he'll survive his birthday the next day.
Grandpa, adorned in a suit and tie, lies in his bed and waits for the clock to strike midnight. The borders are making wagers as to what time Grandpa will "kick the bucket." However, when twelve o'clock finally arrives, Grandpa discovers he is still among the living. He scrolls through his family photo album, recounting the life spans of his relatives, at which point Arnold realizes that his numerous relations didn't really die at 81, but at 91. Overjoyed, Grandpa leaps from his bed, insisting that he's perfectly healthy, and he and Arnold hit the town yet again.