Baum had suggested it be subtitled "An Oz Book," but the publishers decided not to. Perhaps Baum saw "Oz" as a way to help the book sell more strongly rather than suggest it be included as part of the expanded universe of Oz. There's not really a reason why this and the Twinkle Tales couldn't take place in the same universe as the Oz series, however, there are no ties to connect it to the Oz books either. Clearly, Baum was so resigned to being "The Oz Man" by this time, he saw it as his brand.
The story opens with Twinkle and Chubbins walking into a forest with a picnic basket, and when I read it recently, I realized it could easily be picking up directly after Sugar Loaf Mountain, which ends with them leaving the mountain with a picnic basket they haven't eaten from yet.
Suddenly, the trees seem to close in around them, and a spiny-shelled turtle enters, begging to be petted, saying that it was once "a beautiful maiden," enchanted by a cruel tuxix, which is "a magician, a sorcerer, a wizard, and a witch all rolled into one." However, none other than Policeman Bluejay from Bandit Jim Crow flies in and warns them that it is the tuxix herself, trying to trap them. Since the plot is spoiled, the tuxix turns Twinkle and Chubbins into larks, except for their heads, which become small enough to match their bodies.
Policeman Bluejay befriends the two children, leading them to an abandoned nest, and he brings an eagle who brings the basket along so they may eat the food from it. (Since they are now smaller, the food will last longer.)
Twinkle and Chubbins meet their neighbors: the squirrel Wisk who lives in a hollow near the nest, Mrs. Possum, who lives in a hollow at the base of the tree with her four children, and Mrs. Hootaway the grey Owl, who lives in a hollow at the top of the tree. The child-larks (an improvised name for what Twinkle and Chubbins have become) also are visited by many birds who offer stories about how mankind and animals can be so cruel to birds. One of the birds mentions Jim Crow, though Twinkle doesn't seem to think that it was, in fact, her old pet.
The next morning, the child-larks are rudely awakened by hunters who kill all their neighbors (Mrs. Hootaway's dying words are especially poignant: "Remember that—all—is love; all is—love!"), and the child-larks escape with the help of the eagle, whose home they briefly visit.
Policeman Bluejay lets Twinkle and Chubbins take care of orphaned hatchlings, which they find quite tiresome, until he finds another substitute parent.
Then Twinkle and Chubbins are allowed to visit the Paradise of Birds in the middle of the forest, a splendid haven for birds where everything a bird could wish for is instantly provided if it is not already at hand. Music plays always, so there is no need for birds to sing, and there is even a pool of dry water for birds to play in. However, this is quite an exclusive utopia: Twinkle and Chubbins are only allowed entrance because they are not forest birds. However, while there, they are told they may be restored to their true forms if they eat a tingleberry.
Upon leaving, Policeman Bluejay finds his position usurped by the Rooks, and he gathers his friends to fight the Rooks into submission. Then, he helps Twinkle and Chubbins find the tingleberry bush.
Twinkle is restored, but the berry Chubbins ate was partly withered, and he retains his bird's wings. Policeman Bluejay finds another tingleberry, which completes the restoration. And then, as the children leave the forest, they have something surprising for Baum: disorientation at resuming their true forms.
"Don't your legs feel heavy, Twink?"The book takes a few steps forward for the Twinkle Tales. Death is directly addressed as a large number of Twinkle and Chubbins' friends are killed in front of them. While it's sad, it is not written in a way to disturb children.
"Yes," said she; "do yours?"
"Awful," said he.
As a 21st century reader, I can appreciate this. Baum clearly understood that while children shouldn't be terrified, not exposing them to such topics would be a bad thing. For a series aimed at young readers, Baum never talks down to them.
Policeman Bluejay offers an open-ended conclusion to the Twinkle Tales. Baum could have continued with the series, but abstained. He did consider the series some of his best work at one point and even suggested that Twinkle and Chubbins and Policeman Bluejay be reissued in an omnibus edition titled Baum's Wonder Book.
Baum's idea was finally carried out when the book The Twinkle Tales was issued in 2005. Sadly, this edition left out many of the illustrations from the books, only selecting a small few. Twinkle and Chubbins' reprint by the International Wizard of Oz Club included all the illustrations, and Policeman Bluejay was available in a photo-reproduction by Scholar's Facsimiles and Reprints, an edition I do not own. It was also reprinted as the Baum novel in Oz-Story 2, but all of the colored illustrations (I can assume it would have been too much work to remove the color) were dropped there.
The downside to these reprints is that they are generally not available to children, Baum's intended audience, and the design of them is not entirely child-friendly either. Perhaps this will be rectified someday.