The Pearson family is benignly headed by the father, Mr. Pearson, who is the third generation to run the family business, a hardware store. His wife, Mrs. Pearson, is a housewife and mother of three children. Twelve-year-old Joe, the eldest child, is the leader in the electronic mischief, enthusiastically assisted by his ten-year-old brother Stanley. Six-year-old Jenny is the youngest Pearson, and utterly unlike her rambunctious brothers. Hers is a much gentler spirit. Uncle Harold is Mrs. Pearson's younger brother. Twentyeight years old and unmarried, Harold operates an appliance shop in another town. In his enthusiasm for gadgets, Harold is much like his nephews—a bit heedless. He introduces the Pearson boys to the potent hardware without mentioning the need to use it with moderation.

Another important character in the story is Mr. Watson, who never appears in the flesh. Mr. Watson, the...