The “Endling” series by Katherine Applegate, of which “The Only” is the conclusion, is her most powerful story yet. And that’s huge. “The One and Only Ivan” is rightly beloved by almost every student in my elementary school, and by children and adults around the world. It’s a story that grabs hearts and connects readers with the characters in a manner that becomes unforgettable. The “Endling” series, with the first two books, “Endling: The Last” and “Endling: The First” will also grab hearts, and readers will absolutely connect with the narrator, Byx, a Dairne, and practically the last of her species. But readers will also learn about what happens when greed is allowed to reign supreme and when power becomes more important than humanity. It’s a story that follows one young very human-like narrator in a story that’s not only a coming-of-age story but also an allegory about our world. As with “The One and Only Ivan” and all of Applegate’s novels, we are enthralled with her brilliantly drawn characters and the plot that takes us on an emotional rollercoaster.

Applegate doesn’t tone her writing down for kids at all. In true (though often controversial) Disney fashion, at the start of the series, we meet Byx’s family only to have them slaughtered before 50 pages have passed. The first two books are about Byx’s world, wherein we meet the six ruling species. We learn that in Byx’s world, as in ours, humans are perhaps the most destructive of species, their greed and unfettered desire for power causing slaughter and the extinction of many other species. The Dairnes, in fact, have been believed to be extinct, and that’s why Byx’s family took such precautions to hide until their unfortunate murders. What we learn about Byx’s species is that, “… dairnes, it had turned out, were still endangered, walking the thin knife’s edge over the precipice of extinction.”

In the third book, “The Only,” Khara, who saved Byx in the first book, a heroic human determined to stop the destruction and killing of masses of people and animals, has amassed an army to stop an upcoming war between the evil Murdano of Nedarra and the Kazar, the Felivet (like a huge lion) leader of neighboring Dreyland. Her army is called the Army of Peace, and their mission is to stop the violence. But before the armies meet, Khara sends Byx on a few missions as her Ambassador, and we see Byx, who feels young, inexperienced, and incompetent, become a Dairne who excels at making friends via her perspicacity and ability to know when people are telling the truth.

Applegate includes so much detail and information in the pages of this series that while younger middle grade readers will enjoy the story, older middle grade readers and young adult readers (and adults, too!) will be better able to understand some of the complexities and subtleties of the truths that are revealed in the pages. One of the reasons that the Dairnes were slaughtered almost to extinction is a common one even in our world: human desire for their soft and silky fur. Cases in point:The quagga of South Africa, slaughtered to extinction for their unusual and beautiful fur; the warrah, wolves of the Falkland Islands, slaughtered for their fur; the Caribbean monk seals, hunted for their skin and blubber; the only species of parrot native to the United States, the Carolina parakeet was killed to extinction for the beautiful feathers that were sold to adorn hats; the sea mink, native to Maine and north of there was slaughtered to extinction in a short period of time for its fur; and many other species that are now extinct because of humankind’s greed and disregard for the creatures who share our planet.

But the other reason that the Murdano wanted the Dairnes slaughtered is because of their native ability to tell when someone is lying. To corrupt leaders, it’s important to be able to lie with impunity. Applegate writes, “Tyrants have no greater fear than the truth. And if the truth could be known quickly, and by all? What then?” If only there was truly an ability like that—to know if someone is telling the truth or not—in our world. There would be no “alternate facts,” no big lie, no disbelieving of scientific facts. Applegate’s world is a better world in that aspect. But Byx is also a character whom we connect with. When a friend asks her how she got to be so brave, Byx is astounded. She admits that when facing danger, she is scared the whole time. “I don’t think you can stop being scared,” she tells her friend. “I don’t think that’s what it means to be brave. I think being brave means being afraid and still doing what you must.” And that’s an important lesson for children to learn—that even heroes are scared. The heroes in this book understand the sacred duty to fight to do what it right even to the point of being willing to die for those beliefs.

Yet another important message for young readers is that it’s not enough to merely not participate in the evil you might see around you. You must stand up for what is right, what is good, what is important. When Byx and Tobble encounter a pathetic remnant of an extinct species, who has been enchanted and lives on spouting doggerel, he says one important thing: “‘Tis ever easier to hate, than learn or love, or to create.” And finding out about this now-gone species makes Byx and Tobble reflect on true evil and what has been lost. Byx asks, “How many fantastic creatures, how many wonders, how much wisdom has been lost because of those who have the power to destroy?” And Byx shares that it’s easy to do nothing to stop evil, “to see the horror and look away. To do nothing more than mutter and shake your head.” But being a bystander is not enough in Byx’s world, and it’s not enough in our world, either. If reading about the moral imperative to do the right thing will help young people, who one day will be voting and making important decisions, decide to get involved, then every middle grade reader should read this series.

But in spite of the seriousness of much of Applegate’s story, there are also many lighthearted moments, and we love seeing the relationship between the main characters develop and mature, each of them growing and becoming more reflective and thoughtful. One passage that is delightful, for example, is when Byx and Tobble visit a species knows as ragglers, who live in trees. The ragglers tell Byx and Tobble that “the air we breathe comes from trees” to stress how important it is that trees not be cut down. Byx narrates, “It seemed like a quaint notion. Trees making air? But, I supposed, people were free to believe what they wanted.” Young readers will giggle, aware that they know more than the characters in the book!

One extremely minor complaint is that the third book doesn’t have a map of the world through which Byx and Tobble are traveling. I had to go back to a previous book to follow their journey. But that’s a very minor grievance about a series that is so important and so timely—and so beautifully written—that it should be a must-read for all.

Because I’m an educator, though, as much as I want each and every child to read this series, I also wish that each and every child reading this series had a teacher or adult reading it with them so that important concepts and ideas would be discussed and considered. Too often, when children read a novel (and I was guilty of this as a passionate reader who flew through books), they read quickly to get the story and then move on. This book, like so many of Applegate’s novels, is much more than just a story. It’s a story with crucial messages about life, compassion for others, and morals to live by. And to truly understand all of those, it’s often better to have someone to talk to, to discuss the details, ideas, and ideals that the story propounds.

I can’t recommend this series highly enough.

Please note: this review is based on the final, hardcover book provided by the publisher, Harper, for review purposes.