At first Henry's very neat cousin doesn't like the cookies from under his bed or Mudge's slobbery kisses, but when they all play frisbee, she begins to enjoy her visit.
Motor Mouse takes a hot air balloon ride with his brother Valentino and neighbor Horatio, decides to teach Valentino to drive a car, and spends a day with Valentino at the Funfair.
When Henry and his dog Mudge go with Henry's parents to visit Great-Grandpa Bill in the home with lots of other grandpas, they lead them all on a wonderful adventure.