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My son Asher helped me with this trailer, so of course I'm slightly ridiculously proud of it.

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The Casey Grimes Books in Order

Kirkus called The Mostly Invisible Boy “a splendid conception” and no wonder: Casey Grimes thinks his invisibility is permanent until he finds a secret forest society in charge of monster control. Now he’s got a chance to belong—if he can stay alive long enough! "Original and inventive, full of courage and heart" (Amy Wilson, author of A Far Away Magic, Shadows of Winterspell, and The Wild Way Home). 


#1. Need friends?—try fighting monsters.

In this "gripping fantasy adventure" (The Wishing Shelf Book Awards), Casey Grimes begins his studies at Trickery School, one of America's premier monster-control academies. But classes like Extreme Climbing and Land Creature Defense are the least of his worries. He realizes a mysterious enemy is after him—more cunning than a Bog Creep or Hyena Toad. And this secret adversary is playing for keeps. 


#2. Classes have begun. Please don't die. 


#2.5. Don't mind the dragon. 

When Brook, an orphan with a knack for survival, is dumped on a deadly island—by a beast that shouldn’t exist—all she knows is she’s far from her group home in Weed, California. And haunted by a past that stays just out of reach. A stand-alone YA story that also acts as book #2.5 in the Casey Grimes series. 


Side Story: Track the ghost cat! 

Step into the shiny sneakers of the irrepressible Lila Banks as she follows her cat Orangesicle—and fights to survive the night—in a forest where trails move around, strange creatures prowl, and pets are not always what they seem. This short story is a fun, spooky standalone backdoor into the magnificent Casey Grimes world. 


#3. Something's moving in the woods.

Against all odds, Casey Grimes survived the terrible, fiery "Assassin Inferno." That's on top of his dangerous studies at Trickery School. In his second semester, he and Gloria finally have a chance to carve out a home in Sylvan Woods. Unfortunately, something is terribly wrong with the forest itself.

#3.5. Let sleeping dragons lie.

When Conley leaves his safety-obsessed neighborhood and moves to the historic Kansas City Dragon District, he hopes for adventures and new friends. Instead he gets an ancient house with a secret that might roast him alive. So long, summer break.

#4. Spring Break has never been this wild.

Casey Grimes saved the day last semester when he foiled a Jabberwocky plot to carve up Trickery School. With his parents off on their own monster mission, he and Gloria can finally take a break... but their foes have a bone to pick. 

Picture book: Can Gloria be a hero...underwater?

When Gloria takes her paddleboard out for a nice, quiet float, little does she know what waits for her in the sparkly, glittery waters of Sylvan Lake. Our first book for younger readers.

Books & merch are available for purchase in my author shop.


Praise for Casey Grimes

Silver Medal, Wishing Shelf Book Awards 2020

Bronze Medal, Readers' Favorite International Awards Contest 2020


"A steppingstone path of small mysteries and action scenes. Sylvan Woods is a splendid conception... Fast-moving and exuberant, packed with imagination." Kirkus Reviews

"The Mostly Invisible Boy excels...venturing into unpredictable territory, combining the feel of a fantasy with a treasure hunt." – Midwest Book Review


“A fun, exciting read...a rich, enticing world. A true adventure, where the stakes are high, the danger real, and [the] goal is almost impossible to reach.” – Bookworm for Kids


“Brimming with intrigue, danger and humor.” – Book Craic

“Vanderhorst has created a character in Casey Grimes who is so relatable, and so tangible...a must-read fantasy novel for middle grade readers.” – Frank Morelli, author of No Sad Songs and the Please Return To series


"Original and inventive, full of courage and heart."  – Amy Wilson, author of A Far Away Magic, Shadows of Winterspell, and The Wild Way Home


"Fun, funny and imaginative, The Mostly Invisible Boy is a rollicking good adventure."

– Andrew Chilton, author of The Goblin’s Puzzle 

"The Mostly Invisible Boy is a gripping book from start to finish...riveting." – LitPick

"Yikes, Butcher Beasts and Bog Creeps. These monsters have their own agenda. Perfect for middle grade—not too scary but enough to keep you flipping the pages. Surprises at every turn keep the plot moving at a quick pace." – Always in the Middle

“Vanderhorst connects to the deep feelings many middle school children deal with day in and day out.” – Reader’s Favorite five-star review

“Enchanting and unusual…the story entertains from the first page to the last." – Story Sanctuary

"A gripping fantasy adventure." – Wishing Shelf Book Award

"Incredibly imaginative and fun."– Book Pipeline

"Likable characters, clever plot, and unexpected twists and turns." – Indie Reader

“A once-in-a-lifetime adventure. The characters are all so witty and eloquent, and yet the dialogue feels so natural and flowing. The story itself is fast-paced and fun, it doesn’t ever get stuck on anything or leave you bored.” – The Artsy Reader

“AJ Vanderhorst has the most beautiful imagination. The way he puts this world in your mind is nothing short of brilliant. The journey to Sylvan Woods had me on the edge of my seat, and I wouldn’t have it any other way.” – Bookish Bliss

“If you love unique and fun middle-grade fantasy stories with great and interesting characters, a cute little sister you can’t help but love, a forest setting with a school and ‘magical’ community, lots of secrets just waiting to be revealed, monsters, missions and bravery… this is the book for you.” – Read to Ramble

“Kind of gives off treetop Percy Jackson vibes, and I am totally here for it. I would love to get lost in the magical treetop world of Sylvan Woods, but I don’t think I’d like to face all of those awful creatures! There’s a lot of excitement and edge of the seat moments throughout the story, and the ending was no different.” – For Books’ Sake

“This is such a refreshing and delightful depiction of sibling relationships. 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. The over-arching idea of finding where you belong and fighting so that you can stay there is a great one.” – Broken Geek

“This book had me on the edge of my seat.” – Reading Through the Looking Glass

“An engaging and charming Middle Grade Fantasy story…and there’s danger, too.” – I’m a Voracious Reader

“The world with magic trees, vicious monsters, a far-off war that needs preparing for and a tree-top school for future warriors just speaks to my imagination and let it run wild.” – Tirilu

“A bit Harry Potteresque...and what I hope will be a long series of adventures with Casey and his friends. But this is very much an original tale.” – The Strawberry Post

“You aren’t always sure if we are in a world of imagination or magic. The characters are Alice in Wonderlandesque...this would make an amazing cartoon film.” – Books, Occupation…Magic! 

“A new, heightened reality, a world of magic, monsters, honor, adventure, and danger…dynamite worldbuilding and it should be a great world to explore in the volumes to come.” – Irresponsible Reader

"Fun, bold and whimsical…a compelling, entertaining read packed full of magic, escapades and bravery.” – Amy’s Bookish Life

"The adventure these characters go on is incredible and I wish I was right alongside them, battling the creepy monsters, exploring the new world and getting to know all the secrets of Sylvan forest.” – Ellie Mai Blogs

"I loved the hints of magic, the terrifying creatures, and I want to learn everything I can about Sylvan Woods." – Books Are 42

“Gritty for a children’s novel but made in a way that is child-friendly and something that the kids would love!” – Gazer of Books

“A fun and imaginative Middle Grade fantasy read which has at its heart the need to belong.” – Good Night to Read

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The Mostly Invisible Boy: Long Description


Eleven-year-old Casey Grimes 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. Posing as a Sylvan girl’s cousins, he and Gloria enter Trickery School—an academy where classes have surprise endings, battles are as common as breakfast, and magic is so last century. For the first time in his life, Casey makes friends…but kids at Trickery have lost touch with the people they’re sworn to defend. If anyone finds out he’s an imposter, he’ll be blacklisted for life—or worse, thrown in the sewers with the tiger rats.


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.

For kids aged 8+ and adventurous grown-ups.

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