Book Review: The Mostly Invisible Boy by AJ Vanderhorst

Thank you to the author for reaching out and sharing The Mostly Invisible Boy with me. I am happy to read and review middle grade books!

Released: April 25, 2020


Eleven-year-old Casey Grimes is invisible. Really. When he leaves suburbia and infiltrates a secret forest society, he can finally be seen—but Sylvan Woods hates outsiders as much as it loves killing monsters. As Butcher Beasts invade, his flimsy cover story falls apart, and courage is his only chance to belong.

My Thoughts:

Casey Grimes feels nothing but invisible to everyone around him at school, this is also quite true because he truly is invisible (most of the time). He loves to “get away” by climbing trees. This brought me back to my childhood and how much I enjoyed climbing trees too. It would help me “escape” and it was one of those things that you could do alone and still have a great time. When Casey escapes into the woods, he learns more than he imagine. He eventually brings his little sister along this journey, and they discover Sylvan Woods. Side note: I just love their relationship. There is a lot of great sibling humor, which sometimes you don’t see in middle grade books.

This becomes an intriguing adventure and Casey learns a lot about his self-identity and how to overcome his personal obstacles. There is great description of the woods, the monster creatures that come into play, the weaponry, and everything inbetween. This book would be perfect for readers who enjoyed Mulrox and the Malcognitos, as both have mysterious creatures, charming humor, and is set mainly in a magical woods/forest.

Rating: 4 out of 5.

Mostly Invisible Website & Fun

If you want to check out the book trailer and find the hidden page on AJ’s site, click the image below!

About the Author

AJ Vanderhorst has had many jobs, including journalist, paramedic, escape artist, and baby whisperer. One time in fifth grade, he built a traffic-stopping fort in a huge oak tree, using only branches and imagination, and slept there for a week.

Now he and his wife live in a woodsy house with their proteges and a ridiculous number of pets, including a

turtle with a taste for human toes. This makes AJ an expert on wild, dangerous things—invisibility spells, butcher beasts, hungry kids, you get the idea.

He is the only author in the world who enjoys pickup basketball and enormous bonfires, preferably not at the same time. He and his family have drawn up several blueprints for their future tree castle. Visit AJ online at

Wouldn’t it be amazing to escape to another world? I think so! What is your favorite fantasy book? Share with me below!

Xo, Sierra

2 thoughts on “Book Review: The Mostly Invisible Boy by AJ Vanderhorst

Add yours

  1. This sounds like a great novel! It’s neat that both you and the protagonist enjoyed climbing trees—I never did that as a kid, but I can imagine it would be a great way to get away from everything. I also appreciate that the siblings in this book have a great relationship. Thanks for the great review!


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