This episode begins with the children coming home from school to find Nanny in bed with the ""dreaded lergys"". The children are preparing to attend Francine's costume party. When Butch goes into Nanny's trunk to get out some make-up he sees a passport with Nanny's photo giving he date of birth as April 18, 1864, making her 106 years old. Since the 18th is the following day the children prepare to throw her party. The professor keeps trying to get Nanny to reveal her real age. She mentions how she is the image of her great-aunt who lived to a very advanced age. Just as the Professor thinks he has solved the passport riddle Nanny mentions her great-aunt's was a Libra (October).
Professor is working on a computer program. Nanny takes the children in ""Arabella"", her car named after her Aunt. 3 boys laugh at Nanny and the children because of Nanny's car, calling it Yellow Arabella. The 3 boys hassle Butch and Hal about Arabella and they propose a race. Nanny laughs at the prospect of racing Arabella but says there is no race because old cars aren't to be raced, but to be loved for. After Nanny turns the boys challenge of a race down they ask their father who also says he agrees with Nanny. He suggests another way to have a race...using the computer program he has been working on. The bully boys father says his Buckingham will beat Arabella even through the computer race. The boys read all of their car information to the Professor who inputs the data into his computer. The Buckingham wins the computer data race and the Everett boys are disappointed. The family goes for a trip in Arabella and meet up with the Buckingham (magically of course!) along the way.