L. Frank Baum 
The Tin Woodman of Oz / A Faithful Story of the Astonishing Adventure Undertaken by the Tin Woodman, Assisted by Woot the Wanderer, the Scarecrow of Oz, and Polychrome, the Rainbow’s Daughter [PDF ebook] 

A Faithful Story of the Astonishing Adventure Undertaken by the Tin Woodman, Assisted by Woot the Wanderer, the Scarecrow of Oz, and Polychrome, the Rainbow’s Daughter
The Tin Woodman of Oz: A Faithful Story of the Astonishing Adventure Undertaken by the Tin Woodman, Assisted by Woot the Wanderer, the Scarecrow of Oz, and Polychrome, the Rainbow’s Daughter is the twelfth Land of Oz book written by L. Frank Baum and was originally published on May 13, 1918. The Tin Woodman is unexpectedly reunited with his Munchkin sweetheart Nimmie Amee from the days when he was flesh and blood. This was a back-story from The Wonderful Wizard of Oz.
The Tin Woodman and the Scarecrow are regaling each other with tales at the Woodman’s palace in the Winkie Country when a Gillikin boy named Woot wanders in. After he is fed and rested, Woot asks the Woodman how he came made of tin.
He relates how the Wicked Witch of the East enchanted his axe and caused him to chop his body parts off limb by limb, because he was in love with her ward, Nimmie Amee. Each chopped limb was replaced by the tinsmith Ku-Klip with a counterpart made of tin. (Since Oz is a fairyland, no one can die, even when the parts of their body are separated from each other, unless those people are witches and someone drops a house onto them.) Without a heart, the Tin Woodman felt he could no longer love Nimmie Amee and he left her. Dorothy and the Scarecrow found him after he had rusted in the forest (an event related in The Wonderful Wizard of Oz) and went with him to the Emerald City where the Wizard gave him a heart. Woot suggests that the heart may have made him kind, but it did not make him loving, or he would have returned to Nimmie Amee. This shames the Tin Woodman and inspires him to journey to the Munchkin Country and find her.
The Tin Woodman, the Scarecrow, and Woot journey into the Gillikin Country and encounter the inflatable Loons of Loonville, whom they escape by popping several of them. They descend into Yoop Valley, where the giantess Mrs. Yoop dwells, who transforms the travelers into animals for her amusement, just as she has already done to Polychrome, the Rainbow’s Daughter. Woot steals a magic apron that opens doors and barriers at the wearer’s request, enabling the four to escape. Woot, as a green monkey, narrowly avoids becoming a jaguar’s meal by descending further into a den of subterranean dragons. After escaping that ordeal, Woot, the Tin Woodman as a tin owl, the Scarecrow as a straw-stuffed bear, and Polychrome as a canary turn south into the Munchkin Country.
They arrive at the farm of Jinjur, who renews her acquaintance with them and sends to the Emerald City for help. Dorothy and Ozma arrive and Ozma easily restores the Scarecrow and the Tin Woodman to their rightful forms. Polychrome takes several steps to restore to her true form. However, Ozma discovers that the Green Monkey into which Woot is transformed has to be someone’s form; it cannot be destroyed. Polychrome suggests as a punishment for wickedness that Mrs. Yoop the giantess be made into the Green Monkey, and Ozma thus succeeds in restoring Woot to his proper form.
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