Book Review for The Mostly Invisible Boy (Casey Grimes #1) by AJ Vanderhorst

Posted June 11, 2021 by brokengeekdesigns in blogtour, Bookreview / 5 Comments

June4 642x1024 - Book Review for The Mostly Invisible Boy (Casey Grimes #1) by AJ Vanderhorst

Title- The Mostly Invisible Boy (Casey Grimes #1)

Author- AJ Vanderhorst

Publisher- Lion and Co

Publication Date- May 2021 (2nd Printing)

Genre- Mid-grade fantasy

Comments- I was given a free copy via @the_writereads and the author in exchange for an honest review. I was in no way influenced by the Butcher Beasts.


Eleven-year-old Casey is stubbornly friendly, but he’s eternally the new kid at Vintage Woods Middle School. Students look right through him—and they’re not faking. Casey doesn’t know why he’s mostly-invisible, but when he scales a colossal oak, he discovers a fortress in its branches. The forgotten sentry tree marks the border between his safe, suburban life and a fierce frontier.

Casey and his little sister Gloria infiltrate Sylvan Woods, a secret forest society devoted to ancient, wild things. Sky-high footpaths. Survival sewing. Monster control. Shockingly, people here actually see Casey—but being seen isn’t enough. He wants to belong.

Keeping his identity hidden–while struggling to prove he fits–is hard enough, but Butcher Beasts have returned to Sylvan Woods after a hundred years. Trickery is under siege. As the monsters close in, and the fearsome Sylvan Watch hunts Casey down, he and his newfound friends must unearth abandoned magic, buried at the forest’s roots…or be devoured along with everyone else, Sylvans and civilians alike.


We first meet Casey on his last day of Sixth grade, clad in a lime green High Vis vest and brandishing a notebook with last-ditch ideas on how to make people notice him. Because Casey is invisible. Well, mostly. It’s like people look right through him unless he forces them to acknowledge his presence.

invi - Book Review for The Mostly Invisible Boy (Casey Grimes #1) by AJ Vanderhorst

Fed up, Casey returns home for a summer of climbing trees in the woods by his house and hanging out with his younger sister Gloria- his only friend.

In the middle of the woods, Casey finds a special tree that seemingly reaches up forever and is the doorway to a whole new world of dangerous creatures, magic and a secret society dedicated to fighting monsters and protecting civilians.

With his sister in tow, Casey infiltrates the tree-tops, hoping desperately that this is one place he will finally belong. That’s if they survive the night.

With a great initial plot idea this felt somewhat like a Percy Jackson story with a normal boy discovering a magical world that protects the human one.

Casey is such a sweetheart and, other than his mostly invisible tendencies, he doesn’t have any magic powers or ‘Chosen one’ vibes. He is simply a boy who wants to belong and that makes him so appealing. He isn’t overly brave or smart and his averageness helps you identify with him.

I love his relationship with his sister, Gloria. He never disparages her ideas or tells her that she is imagining things. He protects her as much as he can but ultimately lets her stand up for herself. Gloria, in fact, is the heroine in several of their adventures and he never feels slighted by this, instead, he is proud of her achievements. This is such a refreshing and delightful depiction of sibling relationships.

sibling - Book Review for The Mostly Invisible Boy (Casey Grimes #1) by AJ Vanderhorst
It happens. Not often. But it happens.

In a world with magical trees, dangerous beasts, a far-off war and tree-top school for warriors there is such a rich font for the imagination. There might be a few similarities to a certain other fantasy school but these are inevitable and the tale is so diverse that you don’t make the comparison too often, which is also a nice change.

The only downside I will say is that there were several times in the book where I felt I had skipped a paragraph or two. The scene changed without warning or something appeared that hadn’t been there before and I was left floundering, wondering where on earth I had missed something. I had to re-read a few passages numerous times before realising that it wasn’t just me, the information wasn’t there.

There are a few instances where you need to suspend your disbelief and just go with it- like Casey’s parents winning a sudden trip to Jamaica and not bothering to say goodbye to their son. Or the new babysitter ignoring the fact that one of her new charges (who is supposedly ‘normal’) is missing in the woods her entire first night.

parent - Book Review for The Mostly Invisible Boy (Casey Grimes #1) by AJ Vanderhorst
Your problem now.

I imagine that, as it’s a mid-grade book, children would just adjust to the fact that one moment he’s in a wood and the next he’s face down in a swamp, or that a girl appears in a ball of light and it’s never mentioned again. Or the fact that the invisibility thing is solved in a few words later on. As a ‘grown-up’ these things probably bothered me more than they should.


The over-arching idea of finding where you belong and fighting so that you can stay there is a great one. I can see this becoming a really popular book and know several children who I will recommend it to.

An audio excerpt. Something new that I am trying as I would love to be an audiobook narrator.

Click for an excerpt of the story read by @King_lyd. All rights belong to the author and publishing company.
5a133876 60d5 b411 321d 0543493854ba 1024x576 - Book Review for The Mostly Invisible Boy (Casey Grimes #1) by AJ Vanderhorst

5 responses to “Book Review for The Mostly Invisible Boy (Casey Grimes #1) by AJ Vanderhorst

  1. AJ

    I was clicking around, noting reviews so I could reference them on my site, as one does…and came across your audio clip. It was delightful!

    • brokengeekdesigns

      Thank you so much. It was something I was trialling at the time. But wasn’t sure about copyright issues.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.