Of course, that's only two people...
The Master Key is also notable for being the only L. Frank Baum fantasy that was clearly based on his own life. His son Robert experimented with electric gadgets and rigged up devices in the home. While the family noted how useful these experiments could be, they were annoyed by them.
Baum decided to adapt this into The Master Key: we meet the Joslyn family. The father (who is not named), mother Belinda, son Rob, and the daughters Helen and Mabel. Here's Baum's own Gary Stu with a father and son based on himself and daughters, which we understand he would have liked to have had.
The story kicks in when Rob's experiments strike the Master Key of Electricity, summoning the Demon of Electricity. Yes, Baum's works contain good witches and Demons who do not do evil. What a controversial guy...
The definition of Baum's demon is actually found in the World English Dictionary: "an attendant or ministering spirit; genius." And the term "genius" here: "the guardian spirit of a place, group of people, or institution."
So don't worry, The Master Key won't turn people to Satanism.
The Demon gives Rob three gifts a week. The ones featured in the story are a wrist watch-like device that repulses force from its wearer so they may "fly," food tablets that nourish a human body for twenty-four hours, an electric tube (a lot like the weapons in The Boy Fortune Hunters in Yucatan) that paralyzes whoever is shot with it for an hour, a garment that repels any attack, spectacles that reveal anyone's true character, and the "Record" which shows notable events that have happened.
We have things like a couple of the Demon's gifts today: the electric tube is like a taser, though Baum's device is much more benign. The Record of Events we basically have thanks to the Internet, and its portability is similar to tablet devices. Baum even foretells the doom and gloom side of Internet piracy:
During the evening he found that an "important event" was Madame Bernhardt's production of a new play, and Rob followed it from beginning to end with great enjoyment, although he felt a bit guilty at not having purchased a ticket.That last bit also foretells television, though, as we know, it was discovered how to make it profitable.
"But it's a crowded house, anyway," he reflected, "and I'm not taking up a reserved seat or keeping any one else from seeing the show. So where's the harm? Yet it seems to me if these Records get to be common, as the Demon wishes, people will all stay at home and see the shows, and the poor actors 'll starve to death."
Rob's adventures take him from American cities to a cannibal island, to England, to France, to the Middle East, to a deserted island, and even a pirate ship. Along the way, Rob is forced to see the good and evil in humanity and reconsider what technological advances the human race is ready for. Baum wraps together fantasy, adventure, technological speculation and morality to create one of his best and most unique tales.
Quite possibly the most memorable part of the story for Oz buffs is the Demon of Electricity. In John Troutman's Delusionary State, the Demon is accidentally summoned, tying him to Troutman's take on Oz. In an unpublished manuscript I was asked to give feedback on years ago, he is summoned at Smith & Tinker's shop in Ev. Apparently, Oz fans would like to tie this story to Oz for no other reason than to have the Demon of Electricity as an Oz character.
While the Demon is proud and haughty, he's also kind of a jerk. Rob himself points out how fallible the Demon is, but I'm not going to spoil that since I want you to read it for yourself.
The edition I have is a Dover edition that is now out of print. A friend showed me her copy that looks to have been published in 2001 that also reproduced the original edition, just now in hardcover. Also, Books of Wonder published a new edition with new illustrations. However, if you don't mind just going digital (the Demon might prefer that), it's available on Archive.org and Project Gutenberg for free.