I felt the below review from a veteran would give the best overview. Mitch McKinley is with "Law Enforcement Today."

One day, I received a text from our national spokesman that went something like: “I am having a book sent to your house. Could you read it and write a review?” I am no book critic, but I can read and form an opinion, so I took the assignment. The book arrived in the mail a week later. Before we get to that, I need to share two things. One, I am a disabled Army veteran. Two, my 8-year-old son is adopted.
We read this book to my son, a few pages each night, before he went to bed. He was so captivated that he was actually excited for bedtime so he could hear more about Christy, Moxie and, of course, the titular hero, Lucky. And I will not lie, my wife and I were equally captivated.
The story starts with Lucy and her six puppies. Lucy explains that people will be coming to select a puppy to take home to be a part of their families. True to Lucy’s word, people did come, and they played with the pups as they tried to decide which to take home with them. Well, they played with five of them. One of them was ignored and sat watching as his brothers and sisters ran and jumped and interacted with the families in the yard.
See, this sixth puppy was born with a club front paw and had to run on three legs, which caused him to hobble. This puppy sadly tells Lucy: “No one wants me because of my funny paw. I am too different from the rest of my brothers and sisters.” Instantly, our eyes moistened, reading those words and thinking of our own little guy who God blessed us with through adoption. Lucy tells him that someone very special will come and take him to a great home.
The very next day, Christy and Moxie arrived. Moxie was wearing a vest that reads “Service Dog.” Lucky notices that Christy has two prosthetic legs. Asking if she was born that way, like he was born with a club paw, Lucy explained that Christy was injured serving in the Army. At this point, my little boy says: “You were injured in the Army too, Daddy.” Christy decides to take Lucky home to train to be a service dog.
This story for kids teaches so many valuable lessons, such as self-worth, not judging a book by its cover, the reality of bullying, service to others and so many others children need to hear. On the first night reading, my son stopped us a couple of pages in and said, “Lucky is like me. God gave me a family that loves me and wanted me to be in it!”