The book is the fifth one in the Horse Diaries series, and is a wonderful story that combines history, Native American life, and horses.
Much like how the book Black Beauty is narrated by Black Beauty (the horse) himself, Golden Sun is written in a conversational tone and told from the perspective of the horse (also named Golden Sun).
Golden Sun is a chestnut snowflake Appaloosa. During the summer, he treks through the mountains with his rider, a Nez Perce boy named Little Turtle who collects healing plants. He accompanies Little Turtle on his Vision Quest where both realize their true calling.
Golden Sun intersperses words used by the Nez Perce which Olivia and I knew because we had read the Kaya books (an American Girl series about a Nez Perce girl).
The Kaya books had a translation/dictionary in the back to explain what the Nez Perce words meant which was helpful. Having read that series first, we had a greater appreciation and understanding of Golden Sun.
Golden Sun has realistic, beautiful illustrations by Ruth Sanderson. Her ability to capture the detail and beauty of horses is consistent throughout the entire Horse Diaries series.
There is a sixth book in the series that will be released (hopefully) soon. Both Olivia and Sophia are looking forward to reading it.