Merry Go Round in Oz had focused on many new characters, with the classic Oz characters taking a secondary role. This was because Eloise was being very cautious on how to approach such well-established characters, calling these characters "puppets." This time around, likely due to the warm reception of Merry Go Round, the older Oz characters would play a larger role.
In writing their new story, they had many new ideas, but some just didn't seem to work within the context of the story. One that the two writers remembered well was a traveling troupe of live marionettes (eat your heart out, Pinocchio) and a wicked magician named Slyddwyn.
The Forbidden Fountain of Oz was published in 1980 in a uniform edition with Yankee in Oz and The Enchanted Island of Oz, meaning yes, it was another oversize but thin paperback. (The Oz Club now offers a smaller hardcover edition that looks more like an Oz book, and this is the one I own now, though I did trade an older paperback edition for it.)
Forbidden Fountain finds a girl named Emeralda Ozgood getting ready to sell limeade so she can earn money to spend at the Clover Fair.
Yes, the Oz of the McGraws now contains money. As it turns out, Eloise did work out an explanation of how it fit in with Baum saying there was no money in Oz, and she did write it in a footnote that was asked to be removed. She later revealed the footnote at a Winkie Convention. A transcript of her talk (and an audio recording) is available online, courtesy of David Maxine, but with all respect to him, I'm going to quote. (I do highly recommend listening to or reading the entire thing, or both, as it contains quite a bit of information about the McGraws' take on Oz and how Eloise wrote. And anyway, it's difficult to find a recording of any other Royal Historian.)
The money in Oz is rather complex. There are two copper coins, the tiny fardledink and the triangle-shaped squit; five silver coins, the quingle, the quant, the ozzo, the fang and the jeedle; and the gold piozter, which has Ozma's profile on one side and the Royal Crown on the other. To give you some idea of the relative values: three fardle-dinks make a squit, six squits equal a quingle, two quingles make a quant, and three quants an ozzo. There are two ozzos in a jang and five in a jeedle. The piozter is worth ten jeedles. However most people in Oz care little about getting rich, and enjoy using all these coins mainly because they're so pretty. If you are squitless and need to buy something, they will usually make you a present of it.That explanation works for me!
Emeralda makes limeade on the spot using her mother's best pitcher and, accidentally, water from the Fountain of Oblivion. As it turns out, Ozma is her first (and thankfully only) customer. Ozma goes to her garden before she drinks the limeade, and then prompty loses her memory, forgetting who she is and where she is. A butterfly calls her Poppy, so she assumes that must be her name.
Poppy is soon joined by a white lamb named Lambert (the other lambs in his flock are varying shades of purple) and gets new clothes from an old woman. However, they are boy's clothes, and when fully dressed, Ozma, er..., Poppy just about passes for a boy. The only piece of her old clothing she keeps is the Magic Belt, which she feels sure isn't hers.
Back in the Emerald City, it isn't long before Ozma's absence is noted. When the Magic Picture is consulted, it only shows some insects buzzing around. Kabumpo feels sure Ozma must have been kidnapped, so search parties go out. Kabumpo decides to search on his own in the Gillikin Country.
The reason why the Magic Picture showed insects was because Poppy and Lambert drank from Camouflage Creek and it made them blend in with their surroundings, and at the time, they were glitterbugs. Later they change into birds, rabbits, and deer. Finally, they resume their own forms and are about to be robbed by a highwayman when he sees they are a girl and a lamb. This is so discourteous, he refuses to rob them and hearing they are lost, invites them to his cave.
The highwayman introduces himself as Toby Bridecull, and he is attempting to follow in his father's footsteps, but isn't finding the life of a highwayman to his liking. He also has a Suggestion Box that suggests the next course of action, based on the current circumstances, or a drop of oil for itself. They decide they will join some gypsies that Toby declined to join a short time ago.
Toby proves to be an able protector, leading Poppy and Lambert past a dangerous purple wolf, but he's not able to protect them from a gooey lake!
Kabumpo's search takes him to the town of the Wyndups, where the mechanic Clockwise runs everything. Clockwise intends to convert Kabumpo into a clockwork animal, but the elegant elephant of Pumperdink escapes, but soon finds himself in a gooey lake, along with Toby, Poppy, and Lambert. They are in a Bubblegum Gozzer, but manage to escape it with some effort.
The Suggestion Box says that it is an "Auspicious day for surprises," which will soon come. Fortunately for our travelers, they find Pristinia, where everything that isn't clean is cleaned. This gets everyone completely free of the bubblegum that was stuck to them in the gozzer. But they must leave, much to the Pristinians' dismay. (They can't imagine why anyone would risk getting the least bit dirty.)
Along their journey, they come across a Truth Teller who had fallen into the Truth Pond, and the McGraws get to build on that a little: if you lie after having bathed in the Truth Pond, your ears turn bright green. However, when they go to rest, Kabumpo overhears Poppy complaining that her hair never got to dry before her hat was put back on her by Toby, and removing it, Kabumpo recognizes her as Ozma, and decides that she must have been enchanted and kidnapped by Toby!
Kabumpo decides to go back to the Emerald City, but takes a roundabout course so they will not realize what he's doing. (This leads them on a few more merry misadventures.) But when they run into the Truth Teller again, he reveals that they are going south, away from Pumperdink, Kabumpo hurries back, keeping Toby in his trunk. Poppy is dropped off in Ozma's room.
Jack Pumpkinhead recognizes Poppy as Tip at first, and Ozma's memory begins to come back to her, but when Kabumpo publicly calls Toby a villain, Ozma protests his innocence. Emeralda was found by the Wizard as the last person to have seen Ozma and he discovers the recipe of her limeade. However, the Suggestion Box suggests the Magic Belt be used to restore Ozma's memory, which it does.
Toby is made Ozma's bodyguard, and Lambert becomes the latest addition to the Royal Menagerie. Kabumpo's efforts to find Ozma are celebrated in a big party.
And so ends the McGraw's second Oz book. I feel that this time the European influence isn't as heavy, as it only comes in with Toby, and his character is nuanced enough to feel Ozzy: a highwayman who doesn't feel like being a highwayman. Lambert also has an Ozzy trait: he wants to be a colored lamb like the rest of his flock. Unlike other characters like the Cowardly Lion or the Hungry Tiger, he doesn't get over this longing. At the story's end, he is delighted with a bottle of food coloring and hopes Ozma will grant his wish to be eternally green. (Ozma hopes he will change his mind.)
Also, I love the plot. Ozma having her memory wiped makes for a good plot and allows the character to do things she wouldn't ordinarily do. She isn't quite as strong as Tip was back in The Marvelous Land of Oz, but nonetheless, her character is interesting enough to carry the plot.
Kabumpo is a surprising addition to the plot, having been absent since Thompson's own books. He is a very strong character and very much in character, in trying to do the right thing, but remain elegant, but letting his preconceptions get in the way of the actual solution to the problem. In fact, Eloise later admitted that he seemed more "alive" than her original characters in the story. Forbidden Fountain is dedicated to the memory of Ruth Plumly Thompson, and it was wonderful to see someone using one of her characters in a new Oz story at last. (Since Snow, almost all Oz books only used Baum's characters, aside from Thompson's own later books.)
As for the reception of Forbidden Fountain, Oz fans were very glad to have a new Oz story, and it seems the McGraws were pleased to present one. But would they ever come up with another one? Eloise McGraw's Oz stories were only a very small part of her literary output. But she did have some story ideas for Oz that hadn't made it into her first two books. Maybe something could come of this? Time would tell!