The Master Key, an Electrical Fairy Tale Founded Upon the Mysteries of Electricity

The story of the book The protagonist is a boy named Rob Joslyn. His age is not specified. Baum dedicated the book "To My Son, Robert Stanton Baum," who was born in 1886 and would thus have been about fifteen at the time it was published. Rob is an electrical experimenter whose father encourages him and sees that he "never lacked batteries, motors or supplies of any sort.