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Sentinels #1
Sentinels: Keepers of the Forest
Not yet published
Expected 10 Nov 26Discover a world of warring squirrel clans—and meet the chosen ones who will save them—in the start to a new action-packed illustrated middle-grade trilogy perfect for fans of WARRIORS and GUARDIANS OF GA'HOOLE.
Rum is the runt of his litter and an outcast in the Sky Clan, but he sees and understands things the other squirrels don’t—for Rum is a sentinel. Born to each squirrel clan when a catastrophe is looming, sentinels are powerful seers that must go to the Dark Forest to meet a mysterious squirrel that can decipher their message. When Rum befriends the Lowland Clan’s runaway sentinel, Nearly, the two band together to reach the Dark Forest to meet the ancient squirrel, Arundale.
But the message Arundale deciphers is dire: A fire is coming to the mountains that will destroy everything in its path. Only the sentinels can save the forest creatures. But one of their kind, the final sentinel, is missing.
So Rum, Nearly, and a legion of animal protectors set off on an epic journey to find the missing sentinel, and learn her secret message before it’s too late.
Fast-paced and packed with drama and dangerous battles, Sentinels is perfect for reluctant readers and fantasy lovers alike, and filled with captivating illustrations that bring the squirrel world to life.
Rum is the runt of his litter and an outcast in the Sky Clan, but he sees and understands things the other squirrels don’t—for Rum is a sentinel. Born to each squirrel clan when a catastrophe is looming, sentinels are powerful seers that must go to the Dark Forest to meet a mysterious squirrel that can decipher their message. When Rum befriends the Lowland Clan’s runaway sentinel, Nearly, the two band together to reach the Dark Forest to meet the ancient squirrel, Arundale.
But the message Arundale deciphers is dire: A fire is coming to the mountains that will destroy everything in its path. Only the sentinels can save the forest creatures. But one of their kind, the final sentinel, is missing.
So Rum, Nearly, and a legion of animal protectors set off on an epic journey to find the missing sentinel, and learn her secret message before it’s too late.
Fast-paced and packed with drama and dangerous battles, Sentinels is perfect for reluctant readers and fantasy lovers alike, and filled with captivating illustrations that bring the squirrel world to life.
288 pages, Paperback
Expected publication November 10, 2026
About the author
Kate O'Hearn
48 books984 followersKate O'Hearn was born in Toronto Canada, but raised in the heart of New York City and has lived in many places throughout her life. These days, she calls the south coast of England home. She has 3 brothers, no sisters and is passionate about animals and their causes and has many animal friends. (Pets)
Over the course of her life she has had several careers before finding her real love, writing children's books. Being the only girl in family of boys, she grew up a true tom-boy and always loved books with high adventure. But one of the problems she discovered was a lack of female leads in these adventure books.
When she started to write, Kate decided to address this imbalance and now writes high fantasy adventures with strong, compassionate and adventure loving girl heroes. There are plenty of boys in the story to keep it interesting and challenging, but she believes that a girl hero can be as brave, strong and adventurous as a boy.
She insists that adventures are for everyone!
So come and enjoy a few adventures with her...
Over the course of her life she has had several careers before finding her real love, writing children's books. Being the only girl in family of boys, she grew up a true tom-boy and always loved books with high adventure. But one of the problems she discovered was a lack of female leads in these adventure books.
When she started to write, Kate decided to address this imbalance and now writes high fantasy adventures with strong, compassionate and adventure loving girl heroes. There are plenty of boys in the story to keep it interesting and challenging, but she believes that a girl hero can be as brave, strong and adventurous as a boy.
She insists that adventures are for everyone!
So come and enjoy a few adventures with her...
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Displaying 1 - 15 of 15 reviews
Did Not Finish
July 23, 2026DNF. This is REALLY not my thing, but the publisher sent it to me, so I gave it a go.
June 5, 2026
This is a wonderful read for children who love adventure, friendship, and stories with heart. It beautifully reminds us that being different isn’t a weakness—it’s something to be celebrated. Through courage, teamwork, and determination, the story shows how even the smallest individuals can come together to achieve extraordinary things.
A fantastic choice for young readers who enjoy magical adventures and meaningful life lessons. Highly recommended
Review of advance copy received from NetGalley
This was truly the first book I couldn't put down right from the start. It was wonderfully written. I loved the storyline. Each of the characters introduced just added to the depth of the subject matter. This is definitely one that I will recommend to my older grandchildren who can read. I can't wait to see what happens next.
Rum is the runt in his squirrel family. He is always ignored and looked down upon due to his handicap. He meets a squirrel named Nearly, who is also looked down upon in her squirrel family. He knows that he should hate her, due to the warrior like tendencies of her squirrel clan, especially towards his. However, he just can't. This begins a wonderful story of how the two of them find their place in the world and how wonderful they really are. They take an epic journey and along the way meet others like themselves and find they have a special mission. This story is full of fun and suspense and the task of overcoming their personal and collective challenges. Will they overcome all that has been set before them?
This is a must read for families with middle grade children and even some adults I know. It teaches about responsibility not only to family, ourselves and others, but it teaches about how we all need to get along, how hard it can be. You won't regret reading this one.
Rum is the runt in his squirrel family. He is always ignored and looked down upon due to his handicap. He meets a squirrel named Nearly, who is also looked down upon in her squirrel family. He knows that he should hate her, due to the warrior like tendencies of her squirrel clan, especially towards his. However, he just can't. This begins a wonderful story of how the two of them find their place in the world and how wonderful they really are. They take an epic journey and along the way meet others like themselves and find they have a special mission. This story is full of fun and suspense and the task of overcoming their personal and collective challenges. Will they overcome all that has been set before them?
This is a must read for families with middle grade children and even some adults I know. It teaches about responsibility not only to family, ourselves and others, but it teaches about how we all need to get along, how hard it can be. You won't regret reading this one.
Review of advance copy received from NetGalley
Disclaimer: I have been provided an Advance Review Copy by the publisher.
Rum is the runt of his squirrel litter. Born with a disfigured leg, he has to deal with bullying and ostracism from his family and other squirrels. Not only that, he is plagued by the overwhelming need to share The Call, some form of ancient language that is incomprehensible to everyone. His mother warns him to keep it a secret, because squirrels who make The Call are taken away to Dark Forest from which no one ever returns. However, not everything is within his control and The Call must be heard...
Squirrel fantasy xenofiction! Apparently that has been a thing before, but they haven't been a popular choice for animal fantasy. But I'm always eager to see new positions in the subgenre so I was eager to check it out.
So, how does it do? It's... Fine. I read it and sort of enjoyed it, but it's clearly missing something more. It's probably as straightforward a take on the genre as possible. Which probably won't be a big deterrent for the intended audience.
I liked the main cast, though out of the five Chosen ones only Rum and Nearly get decent characterisation and development, the others are mostly just kind of there.
The pacing is very energetic, there's always something happening. It seems to be a new trend with the books to keep things going fast and I didn't really mind it here. It did seem to know when to take a bit of a breather but never overstayed its welcome.
The story is the weak spot. It feels like the most classic take on the hero's journey and on one hand that's fine, on the other hand I wished the author put more of herself into it and came up with at least a bit of something fresh. The outcast main character ending up becoming the chosen one hero also seems extremely prevalent in xenofiction which only adds to it feeling derivative.
There's also the matter of the main villain, who is done extremely poorly and doesn't help to properly establish the threat. The way in which he is defeated is also extremely disappointing and anticlimactic.
On the other hand, the artist responsible for the cover and inside illustrations (and there are a lot of them) did an amazing job. So lively and cute, they were always a joy to look at.
It's not a terrible book, but it does feel a bit stale in its concepts. Despite that, it's executed well for the most part and it was a fast and pleasant read. I think if the author can take some creative risks and try to innovate a bit it could become a good series, as it is, it's only decent.
3.5 a star for me, rounded up for the amazing artwork.
Rum is the runt of his squirrel litter. Born with a disfigured leg, he has to deal with bullying and ostracism from his family and other squirrels. Not only that, he is plagued by the overwhelming need to share The Call, some form of ancient language that is incomprehensible to everyone. His mother warns him to keep it a secret, because squirrels who make The Call are taken away to Dark Forest from which no one ever returns. However, not everything is within his control and The Call must be heard...
Squirrel fantasy xenofiction! Apparently that has been a thing before, but they haven't been a popular choice for animal fantasy. But I'm always eager to see new positions in the subgenre so I was eager to check it out.
So, how does it do? It's... Fine. I read it and sort of enjoyed it, but it's clearly missing something more. It's probably as straightforward a take on the genre as possible. Which probably won't be a big deterrent for the intended audience.
I liked the main cast, though out of the five Chosen ones only Rum and Nearly get decent characterisation and development, the others are mostly just kind of there.
The pacing is very energetic, there's always something happening. It seems to be a new trend with the books to keep things going fast and I didn't really mind it here. It did seem to know when to take a bit of a breather but never overstayed its welcome.
The story is the weak spot. It feels like the most classic take on the hero's journey and on one hand that's fine, on the other hand I wished the author put more of herself into it and came up with at least a bit of something fresh. The outcast main character ending up becoming the chosen one hero also seems extremely prevalent in xenofiction which only adds to it feeling derivative.
There's also the matter of the main villain, who is done extremely poorly and doesn't help to properly establish the threat. The way in which he is defeated is also extremely disappointing and anticlimactic.
On the other hand, the artist responsible for the cover and inside illustrations (and there are a lot of them) did an amazing job. So lively and cute, they were always a joy to look at.
It's not a terrible book, but it does feel a bit stale in its concepts. Despite that, it's executed well for the most part and it was a fast and pleasant read. I think if the author can take some creative risks and try to innovate a bit it could become a good series, as it is, it's only decent.
3.5 a star for me, rounded up for the amazing artwork.
Review of advance copy received from Publisher
What worked:
Young readers will love the main characters, which are different varieties of squirrels. The author includes facts about the animals to keep them “realistic” and relatable. Common predators are a constant danger, such as hawks, foxes, and skunks. The characters must forage for food and seek shelter from their enemies and nature. Rum has visions of possible future events and dangers, and he warns his clan about a severe, deadly snowstorm and attacking predators. He’s joined by a Lowland squirrel named Nearly, and she has a keen sense of her surroundings. Her ability seems similar to Rum's, although she can’t sense things that haven’t happened yet.
Readers will feel empathy for Rum, as the other squirrels, including his brothers and sisters, don't accept him. He’s the smallest squirrel in his litter, and his deformed leg makes it harder to navigate his home and environment. He frequently feels an overwhelming need to scream, but he knows he must keep it secret. He’ll be banished from his home and clan if any of the other squirrels find out. Readers will think highly of Rum, since he’s the only member of his family willing to help their mother care for three new baby sisters. His empathy for others is evident throughout the book, and it’s probably a big reason why Nearly becomes his best friend. In return, she often acts as his protector.
Prejudice and understanding are big issues. All of the sentinels are different from the other squirrels in their clans, and they’re shunned, mocked, or feared. The five different squirrel clans are very territorial, and they never work together. None of the forest animals cooperate, and the smaller, weaker animals are often at the mercy of the stronger ones. Rum’s abilities allow him to make seemingly risky choices by spreading understanding and compassion for prickly or dangerous characters. The sentinels’ calls cause former foes to join forces to protect them during their journey to the Dark Forest. One evil antagonist disrupts their quest, and his misguided plans may spell doom for the entire forest.
What didn’t work as well:
The summary on the back of the book tells readers a deadly fire is coming, but the story doesn’t reveal that information until it's nearing the end. This huge surprise should have been left for readers to discover on their own. The back cover spoils the mystery of the sentinel’s message.
The final verdict:
Young readers will enjoy the animal characters and the sentinels’ determination to save the forest. There’s even a good deal of suspense and action for adventure lovers. I recommend you read this first book in an inspirational new series.
Young readers will love the main characters, which are different varieties of squirrels. The author includes facts about the animals to keep them “realistic” and relatable. Common predators are a constant danger, such as hawks, foxes, and skunks. The characters must forage for food and seek shelter from their enemies and nature. Rum has visions of possible future events and dangers, and he warns his clan about a severe, deadly snowstorm and attacking predators. He’s joined by a Lowland squirrel named Nearly, and she has a keen sense of her surroundings. Her ability seems similar to Rum's, although she can’t sense things that haven’t happened yet.
Readers will feel empathy for Rum, as the other squirrels, including his brothers and sisters, don't accept him. He’s the smallest squirrel in his litter, and his deformed leg makes it harder to navigate his home and environment. He frequently feels an overwhelming need to scream, but he knows he must keep it secret. He’ll be banished from his home and clan if any of the other squirrels find out. Readers will think highly of Rum, since he’s the only member of his family willing to help their mother care for three new baby sisters. His empathy for others is evident throughout the book, and it’s probably a big reason why Nearly becomes his best friend. In return, she often acts as his protector.
Prejudice and understanding are big issues. All of the sentinels are different from the other squirrels in their clans, and they’re shunned, mocked, or feared. The five different squirrel clans are very territorial, and they never work together. None of the forest animals cooperate, and the smaller, weaker animals are often at the mercy of the stronger ones. Rum’s abilities allow him to make seemingly risky choices by spreading understanding and compassion for prickly or dangerous characters. The sentinels’ calls cause former foes to join forces to protect them during their journey to the Dark Forest. One evil antagonist disrupts their quest, and his misguided plans may spell doom for the entire forest.
What didn’t work as well:
The summary on the back of the book tells readers a deadly fire is coming, but the story doesn’t reveal that information until it's nearing the end. This huge surprise should have been left for readers to discover on their own. The back cover spoils the mystery of the sentinel’s message.
The final verdict:
Young readers will enjoy the animal characters and the sentinels’ determination to save the forest. There’s even a good deal of suspense and action for adventure lovers. I recommend you read this first book in an inspirational new series.
Review of advance copy received from NetGalley
Sentinels: Keepers of the Forest is the first book in a new illustrated middle grade trilogy from Kate O'Hearn, and it lands squarely for its target audience of readers around ages 8 to 12. The story follows Rum, the runt of his squirrel litter and an outcast in the Sky Clan, who turns out to be a sentinel, a rare seer born when disaster is coming. When he teams up with Nearly, a runaway sentinel from a rival clan, the two set off toward the Dark Forest and discover a fire is coming that could destroy everything. Johanna Tarkela's illustrations are lively and charming throughout, and fans of Warriors and Guardians of Ga'Hoole will feel right at home.
For me as an adult reader, the writing felt quite simple and a bit childish, which is fair enough given who it is written for. It is a good setup for a heroic triumph, with the overlooked "runts" of the litter banding together to save an entire forest, and that underdog message has real heart. My main wish was for more real biology woven into the story. There is a nice moment contrasting ground squirrels and flying squirrels, but I kept hoping to learn more about how squirrels actually live as I followed the adventure, and that layer of natural history never fully arrived.
That said, this book is carrying a lot of world building and backstory, so it makes sense that so much space goes to introducing the clans, the sentinels, and the rules of this world. I suspect the next books in the series will really ramp up now that the foundation is laid. Young readers who love animal adventures and want the next thing to hand a Warriors fan will enjoy this one, and I am curious to see where the trilogy goes from here.
For me as an adult reader, the writing felt quite simple and a bit childish, which is fair enough given who it is written for. It is a good setup for a heroic triumph, with the overlooked "runts" of the litter banding together to save an entire forest, and that underdog message has real heart. My main wish was for more real biology woven into the story. There is a nice moment contrasting ground squirrels and flying squirrels, but I kept hoping to learn more about how squirrels actually live as I followed the adventure, and that layer of natural history never fully arrived.
That said, this book is carrying a lot of world building and backstory, so it makes sense that so much space goes to introducing the clans, the sentinels, and the rules of this world. I suspect the next books in the series will really ramp up now that the foundation is laid. Young readers who love animal adventures and want the next thing to hand a Warriors fan will enjoy this one, and I am curious to see where the trilogy goes from here.
Review of advance copy received from NetGalley
I had the opportunity to read an Advance Reader Copy of Sentinels: Keepers of the Forest by Kate O’Hearn. Overall, this was an average read for me, but there were some things I really appreciated about it.
What I enjoyed most was the focus on the unlikely, flawed characters — the runts, the outsiders, even the flying squirrel who can’t fly. I always love stories where the ones others overlook end up showing real courage and heart, and this book did that well.
I also appreciated the message woven throughout the story: standing up, speaking the truth, and coming together across differences to save everyone. There was something really meaningful about seeing different species work together, especially when it would have been easier to stay divided. That theme gave the story a lot of heart.
While it wasn’t a standout book for me, I did enjoy the reminder that strength often comes from the most unexpected places. If you enjoy animal adventures with themes of courage, truth, and unity, this one may be worth checking out.
What I enjoyed most was the focus on the unlikely, flawed characters — the runts, the outsiders, even the flying squirrel who can’t fly. I always love stories where the ones others overlook end up showing real courage and heart, and this book did that well.
I also appreciated the message woven throughout the story: standing up, speaking the truth, and coming together across differences to save everyone. There was something really meaningful about seeing different species work together, especially when it would have been easier to stay divided. That theme gave the story a lot of heart.
While it wasn’t a standout book for me, I did enjoy the reminder that strength often comes from the most unexpected places. If you enjoy animal adventures with themes of courage, truth, and unity, this one may be worth checking out.
Review of advance copy received from NetGalley
I love to read stories about forest creatures, especially well-written stories that capture what it might be like to be a squirrel living in a big forest. Kate O'Hearn's Sentinels: Keepers of the Forest captures the reader and takes you to that animal world.
The character Rum is an outcast, and different from the rest of his clan. He was born with the strange and terrifying need to call that he must hide from the clan. As Rum ventures away to be alone at his secret place by the waterfall; he makes a new friend that also has the urge to call. What is this call and what are Rum and his friend supposed to do with it? Rum's adventure is action packed, including aggressive battles amongst different animals. This story is not just about animals in a forest but about their survival, and their ability to see past their differences to unite and protect each other as danger looms in the distance. The book is accompanied by some beautiful illustrations, a must read for fans of animal stories.
I received this ARC in exchange for an honest review.
The character Rum is an outcast, and different from the rest of his clan. He was born with the strange and terrifying need to call that he must hide from the clan. As Rum ventures away to be alone at his secret place by the waterfall; he makes a new friend that also has the urge to call. What is this call and what are Rum and his friend supposed to do with it? Rum's adventure is action packed, including aggressive battles amongst different animals. This story is not just about animals in a forest but about their survival, and their ability to see past their differences to unite and protect each other as danger looms in the distance. The book is accompanied by some beautiful illustrations, a must read for fans of animal stories.
I received this ARC in exchange for an honest review.
Review of advance copy received from NetGalley
Rum is not your typical, young squirrel. He's smaller - the runt of the litter - not well liked, and was born with a leg that doesn't work like it should. He's not what you would consider the hero of a story. However, his journey through this book helps prove that he is more than his limitations. This book really kept the story moving along at a fast pace, with secrets being revealed, friendships being made, teamwork and bravery taking center stage, and characters showing real growth along the way. I really appreciated how relationships were made and portrayed. The importance of family and friends and how they help us along our journey is a central theme. The ending was satisfying and definitely leads right into the next in the series. Thank you to the publisher and NetGalley for an ARC copy of this book. My review reflects my honest opinion.
Review of advance copy received from NetGalley
Sentinels: Keepers of the Forest is an exciting start to a new series for readers who also like Redwall, Warriors, and anyone who enjoys animals as the main characters.
The world's magic channels through and around the mysterious Sentinels, some who don't even know what they are. Through the story they discover how they are meant to help and protect the land. Themes of self-discovery, sacrifice, and found family give plenty to think on and discuss.
As an avid reader of Middle Grade and YA fiction, I'd say this is appropriate for 10 and up due to scary/intense scenes, including fighting and natural disaster.
The world's magic channels through and around the mysterious Sentinels, some who don't even know what they are. Through the story they discover how they are meant to help and protect the land. Themes of self-discovery, sacrifice, and found family give plenty to think on and discuss.
As an avid reader of Middle Grade and YA fiction, I'd say this is appropriate for 10 and up due to scary/intense scenes, including fighting and natural disaster.
Review of advance copy received from NetGalley
They say ‘don’t judge a book by its cover’ but I did with this book, and in the best way. I fell in love with the squirrels on the cover and had to know what this book was about - and it didn’t disappoint. Keepers of the Forest was filled with drama and action, as well as emotion and life lessons for all ages. This is a great start to what I hope will be a multi-book series. I enjoyed it as an adult, and I’m sure my students will as well. I will be recommending this book for our fall/winter library book purchase.
I received an ARC of this novel from NetGalley.
I received an ARC of this novel from NetGalley.
Review of advance copy received from Edelweiss+
E ARC provided by Edelweiss
This reminded me a bit of Hill's 2016 LUCKY, and will be a huge hit with fans of Sutherland's Wings of Fire of Hunter's Warrior cat books. I don't think I will buy a copy, as this author's FLAMES OF OLYMPUS series hasn't circulated recently, although with all of the interest in Greek mythology caused by this summer's THE ODYSSEY movie, maybe I should brush those off.
This reminded me a bit of Hill's 2016 LUCKY, and will be a huge hit with fans of Sutherland's Wings of Fire of Hunter's Warrior cat books. I don't think I will buy a copy, as this author's FLAMES OF OLYMPUS series hasn't circulated recently, although with all of the interest in Greek mythology caused by this summer's THE ODYSSEY movie, maybe I should brush those off.
Review of advance copy received from Netgalley
This is the next book you give to your Warriors fan!
As a kid, I loved books where animals work together and Sentinels delivers that and more! Featuring an outcast squirrel who cares for others in a clan that is every squirrel for themselves, this book is about cooperation, destiny, and epic animal battles!
Highly recommend Sentinels and cannot wait for the next one!
As a kid, I loved books where animals work together and Sentinels delivers that and more! Featuring an outcast squirrel who cares for others in a clan that is every squirrel for themselves, this book is about cooperation, destiny, and epic animal battles!
Highly recommend Sentinels and cannot wait for the next one!
Read
July 25, 2026A great adventurous story. The story is about squirrel clans and something terrible is coming. And the sentinels need to come together to deliver the message to save all the clans.
I thought it was a good read. Very much like the books about the cat clans.
I thought it was a good read. Very much like the books about the cat clans.
September 12, 2026
3.5 ⭐️
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