In the book, a country mouse named Timmy Willie is accidentally carried to a house in the town in a hamper full of vegetables. The town house is home to a great many mice, including the title character Johnny Town-Mouse. Although Johnny Town-Mouse tries hard to make Timmy Willie feel welcome in his new home, Timmy Willie does not like the food or the noises in the town and is afraid of the cat in the house. He eventually leaves the town the same way that he came. Several months later, following an intense effort to rid the house of mice, Johnny Town-Mouse visits Timmy Willie's country home with a view to possibly staying there permanently. He soon finds, however, that country life does not suit him.