The book's heroine is an "honest and industrious" goat-girl named Mandy, who grazes her flock on the slopes of Mt. Mern (an otherwise unidentified location).
The story opens with a bang and a splash: an underground spring erupts in a geyser that blasts Mandy into the sky. The force propels her across the Deadly Desert to Oz; she lands in the principality of Keretaria in the Munchkin Country, her impact cushioned by the influence of a magic blue daisy. Mandy finds a silver hammer, and meets an ox with golden horns; she blunders into the court of King Kerr and his nobles. They are outraged at the intrusion of such an outlandish figure — for Mandy has seven arms and hands. As the girl explains,
- "This iron hand...I use for ironing, lifting hot pots from the stove and all horrid sort of work; this leather hand I keep for beating rugs, dusting, sweeping and so on; this wooden hand I use for churning and digging in the garden; these two red rubber hands for dishwashing and scrubbing, and my two fine white hands I keep for holding and braiding my hair."
For her part, Mandy is amazed to meet so many two-handed people; on Mt. Mern everyone has seven hands.
Mandy is reprieved from the dungeons by Nox the Royal Ox, who takes her as his "slave." It is a benign kind of slavery; the two become friends, and Nox gives her her "handy" nickname. Nox is preoccupied by the Keretarian political situation: the rightful king, a boy named Kerry, has disappeared, and the throne has been usurped by his uncle Kerr. The Royal Ox is an unusual creature: his right horn grants wishes, and his left horn offers clues. When a clue indicates that King Kerry can be found at a place called the Silver Mountain, the enterprising Mandy leads Nox on a search for the missing monarch.
They swim rivers (Mandy can't swim) and survive a flood on their way to the Gillikin Country. A doorway hidden under a waterfall leads them to a subterranean realm within Silver Mountain, a fantastic place of silvery filigree lit by glowing amethysts. The domain is ruled by an evil and ambitious tyrant called the Wizard of Wutz. His throne sits in a pool of mercury, bordered by lavender sands. Wutz is plotting to steal the main magical artifacts of Oz, including the Magic Picture and the Great Book of Records, as a prelude to conquest. As part of his plan, Wutz keeps Kerry prisoner, and has obtained the jug that is the confinement vessel of Ruggedo the Gnome King (he was transformed into a jug at the end of Thompson's Pirates in Oz).
Wutz's machinations begin to work. His efforts of course attract the attention of Princess Ozma and her friends and allies; but their responses are limited, since they are missing the Magic Picture and the Great Book of Records.
Mandy and Nox confront the Wizard of Wutz; he imprisons them in the depths of his realm. Mandy accidentally liberates Ruggedo, merely by breaking his jug. Wutz and Ruggedo instantly become allies in evil (though deeply mistrustful ones), and together they set off for the Emerald City to complete their conquest. Mandy's silver hammer, though, proves to be magic; striking it calls forth a helpful purple elf. With hammer and elf, blue daisy, and Nox's horns, they have enough magic to escape confinement, find and rescue King Kerry, and reach Ozma's Palace in time to frustrate Wutz and Ruggedo. The elf, who calls himself Himself, transforms the two villains into potted cacti.
Ozma restores order with her Magic Belt. Wutz's spies and agents are turned into moles. Kerry is restored to his throne. Mandy is rewarded with an emerald necklace and a luxury she has longed for — gloves: Ozma gives her seven sets of seven gloves for her seven hands. After a month at home on Mt. Mern, Mandy returns to Oz (with her goats) via wishing pill, for a new life.
The plot of Handy Mandy strongly resembles the plot of L. Frank Baum's eleventh Oz book, The Lost Princess of Oz, in which Ugu the Shoemaker steals magical artifacts and kidnaps a ruler in a conquest plot, just like the Wizard of Wutz. Indeed, Thompson is open about the similarity: she has Trot comment on the resemblance in Chapter 14 of Handy Mandy.
Ruggedo's appearance here is his final role in the "Famous Forty" Oz books — though he returns in the works of later Oz authors. [For examples, see Dr. Angelina Bean in Oz, The Raggedys of Oz, The Medicine Man of Oz, A Grown-Up in Oz and Ruggedo in Oz.]
Thompson's character creations are not always highly imaginative: a circus elephant (Kabumpo), a medieval knight (Sir Hokus of Pokes), a circus clown (Notta Bit More), fall short of Baum's great grotesques. Handy Mandy, however, is a triumphant realization of a unique figure. Mandy taxed the artistic abilities of John Neill, though he was fairly consistent in giving her three left hands and four rights.
Thompson later composed a 48-line poem on Mandy's origin — though this origin is inconsistent with the novel. In the poem, Mandy is an artificially created being, built by Sir Solomon Tremendous Wise, made of "wood and tin...wire and cloth and plaster...." She was built as a sort of domestic robot to perform housework. The novel, in contrast, clearly indicates that Mandy, despite her inanimate parts of iron and wood and rubber, comes from a race of seven-handed people.
The poem was published in Oz-story Magazine No. 1 in 1995.
Atticus Gannaway includes the elf Himself and the silver hammer in The Silver Sorceress of Oz. Marcus Mebes employs Handy Mandy in his novel Lurline and the White Ravens of Oz. Nathan DeHoff devoted one of his Oz stories to Handy Mandy. 
|Ruth Plumly Thompson's Oz books|