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Monster Down Deep
YACHT SINKS! JEWELLERY LOST! MASSIVE REWARD OFFERED!
Ever since the shipwreck, California's golden coast has been filled with treasure hunters. Each one is after the same the lost diamond necklace. But none are more determined than Cassie Stein. Her dad's beloved aquarium is falling apart, and they need money - fast!
While racing to find the treasure before her rival, TJ, Cassie finds something remarkable. A fish, unlike any she has ever seen, that can understand her every word. His name is Blue, and his life is in grave danger.
To save her new friend, Cassie must do the unthinkable - accept TJ's help. But with the diamond necklace still up for grabs, can she really trust him?
Ever since the shipwreck, California's golden coast has been filled with treasure hunters. Each one is after the same the lost diamond necklace. But none are more determined than Cassie Stein. Her dad's beloved aquarium is falling apart, and they need money - fast!
While racing to find the treasure before her rival, TJ, Cassie finds something remarkable. A fish, unlike any she has ever seen, that can understand her every word. His name is Blue, and his life is in grave danger.
To save her new friend, Cassie must do the unthinkable - accept TJ's help. But with the diamond necklace still up for grabs, can she really trust him?
- GenresMiddle Grade
304 pages, Kindle Edition
Published February 12, 2026
21 people want to read
About the author
Amy Fellner Dominy
11 books259 followersHi! I write contemporary books for kids and teens and anyone who loves adventure, nature, laughter and a bit of magic. Coming in 2026: MONSTER DOWN DEEP, a middle grade adventure and A HOUSE WITH NO DOOR, a picture book about the harvest holiday of Sukkot. For news, giveaways and sneak peeks, sign up for my monthly newsletter at www.amydominy.com/newsletter. Thanks for following me here!
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Displaying 1 - 7 of 7 reviews
Review of advance copy received from Edelweiss+
E ARC provided by Edelweiss Plus
Cassie and her father live on the coast of Southern California, where her father is an aquarist for the small Mayim Aquarium. Her mother, who was also interested in the well being of the ocean and its creatures, was killed in a car accident when Cassie was three. There has recently been a yacht crash in the area that resulted in the loss of a lot of expensive jewelry, and the Royce family has offered a million dollar reward for the return of a particularly elaborate $50 million dollar necklace. Cassie, along with her Hunter Pro Series 2 metal detector named Sylvia (after marine biologist Sylvia Earle), is determined to find the item. What she finds instead is Blue, a very odd fish, whose point of view is shared in some chapters. Blue is caught in a fishing net and a lot of seaweed, and seems to understand when Cassie communicates with him. Cassie is not happy to see a “Mystery Thief", a boy her age who is also looking for the necklace, but gets to know TJ, who is staying along the beach with his uncle while his father and pregnant mother are back home in Carlsbad while the mother is on bedrest. Cassie spends a lot of time on the beach, nominally supervised by local artist Miss Mary, and when she sees Blue being menaced by a seven gill shark, she immediately goes to her father for help. Unfortunately, he is in a very important meeting with the new directors of the aquarium, but manages to save Blue. Since Blue is very unusual, he becomes a cause celebre in the news, but also isn’t treated well by the new directors. Will Cassie be able to continue to search for the necklace but also save Blue?
Strengths: Treasure hunts are always popular, and the ocean is an interesting place for them, which we see in novels like Rodriguez’s Treasure Tracks or Collard’s Double Eagle. Combining this activity with saving an unusual fish and an interesting small aquarium makes for an intriguing story. I was glad to see that Cassie didn’t fight with TJ the entire time, but learned to work with him. There is a little bit of friend drama with two of Cassie’s sometimes friends, both realistically named Emma! Cassie’s family is Jewish (as are many of Dominy’s characters, going back to her 2011 OyMG), as are the owners of the aquarium, and I enjoyed how the Jewish concept of tikkun olam was explained and demonstrated.
Weaknesses: This almost verged into fantasy, with Blue seeming to understand Cassie’s communication, but it remains a realistic fiction book. While it is admirable that Cassie wants to save Blue, releasing him back to a dangerous situation in the ocean while ignoring the recommendations of her father made me uncomfortable. It didn’t help that the dead parent trope was embraced even though it did nothing to enhance the plot. The ending is happy, but a little unbelievable.
What I really think: This is a good choice for readers who enjoyed aquatic preservation adventures like Dimopoulos' Turn the Tide, Baskin’s and Polisner’s Consider the Octopus, Kelly’s Three Blue Hearts, or Pyron’s Octopus Moon.
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Cassie and her father live on the coast of Southern California, where her father is an aquarist for the small Mayim Aquarium. Her mother, who was also interested in the well being of the ocean and its creatures, was killed in a car accident when Cassie was three. There has recently been a yacht crash in the area that resulted in the loss of a lot of expensive jewelry, and the Royce family has offered a million dollar reward for the return of a particularly elaborate $50 million dollar necklace. Cassie, along with her Hunter Pro Series 2 metal detector named Sylvia (after marine biologist Sylvia Earle), is determined to find the item. What she finds instead is Blue, a very odd fish, whose point of view is shared in some chapters. Blue is caught in a fishing net and a lot of seaweed, and seems to understand when Cassie communicates with him. Cassie is not happy to see a “Mystery Thief", a boy her age who is also looking for the necklace, but gets to know TJ, who is staying along the beach with his uncle while his father and pregnant mother are back home in Carlsbad while the mother is on bedrest. Cassie spends a lot of time on the beach, nominally supervised by local artist Miss Mary, and when she sees Blue being menaced by a seven gill shark, she immediately goes to her father for help. Unfortunately, he is in a very important meeting with the new directors of the aquarium, but manages to save Blue. Since Blue is very unusual, he becomes a cause celebre in the news, but also isn’t treated well by the new directors. Will Cassie be able to continue to search for the necklace but also save Blue?
Strengths: Treasure hunts are always popular, and the ocean is an interesting place for them, which we see in novels like Rodriguez’s Treasure Tracks or Collard’s Double Eagle. Combining this activity with saving an unusual fish and an interesting small aquarium makes for an intriguing story. I was glad to see that Cassie didn’t fight with TJ the entire time, but learned to work with him. There is a little bit of friend drama with two of Cassie’s sometimes friends, both realistically named Emma! Cassie’s family is Jewish (as are many of Dominy’s characters, going back to her 2011 OyMG), as are the owners of the aquarium, and I enjoyed how the Jewish concept of tikkun olam was explained and demonstrated.
Weaknesses: This almost verged into fantasy, with Blue seeming to understand Cassie’s communication, but it remains a realistic fiction book. While it is admirable that Cassie wants to save Blue, releasing him back to a dangerous situation in the ocean while ignoring the recommendations of her father made me uncomfortable. It didn’t help that the dead parent trope was embraced even though it did nothing to enhance the plot. The ending is happy, but a little unbelievable.
What I really think: This is a good choice for readers who enjoyed aquatic preservation adventures like Dimopoulos' Turn the Tide, Baskin’s and Polisner’s Consider the Octopus, Kelly’s Three Blue Hearts, or Pyron’s Octopus Moon.
https://msyinglingreads.blogspot.com/...
https://msyinglingreads.blogspot.com/...
https://msyinglingreads.blogspot.com/...
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https://msyinglingreads.blogspot.com/...
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Review of advance copy received from Publisher
Entertaining, eco-friendly treasure/aquarium story.
A girl who's afraid of the water. A fish who's caught in the seaweed. A treasure everyone is searching for. A possible Missing Link. Ooohh, lots fit in here, but it's neatly done.
Cassie is beachcombing with her trusty metal detector along with many others, after a billionaire's yacht capsizes, sending precious jewels overboard and into the water and a $1 million reward for a necklace. While trying to overcome the fear that's lost her friends, Cassie spots an unusual looking fish caught in some extensive seaweed, and realises that he's not like any other fish she's ever seen, but also somehow able to communicate with her.
Cassie's dad works in the local aquarium, making her well placed to know a lot about aquatic life, and to send this little fish's life into a tailspin (so to speak), as he needs rescuing before the sharks are able to reach him... but if he's taken to the aquarium and it's found he really is an undiscovered species as Cassie and her new human treasure-seeking frenemy suspect, he could have moved out of the frying pan and into a fire - or tank - just as deadly.
Bit of a friendship and trust story, eco-tale, treasure seeking and even an escape plot. We get Blue and Cassie telling their sides of the story, with Blue nicely conveying how a fish might view the human world. And Cassie being the moral heart.
Enjoyed it, not too preachy, lots of good interplay between Cassie and her friends/dad, it felt like Free Willy or similar water-animal stories.
For ages 9-13.
With thanks to the publisher for providing a review copy.
A girl who's afraid of the water. A fish who's caught in the seaweed. A treasure everyone is searching for. A possible Missing Link. Ooohh, lots fit in here, but it's neatly done.
Cassie is beachcombing with her trusty metal detector along with many others, after a billionaire's yacht capsizes, sending precious jewels overboard and into the water and a $1 million reward for a necklace. While trying to overcome the fear that's lost her friends, Cassie spots an unusual looking fish caught in some extensive seaweed, and realises that he's not like any other fish she's ever seen, but also somehow able to communicate with her.
Cassie's dad works in the local aquarium, making her well placed to know a lot about aquatic life, and to send this little fish's life into a tailspin (so to speak), as he needs rescuing before the sharks are able to reach him... but if he's taken to the aquarium and it's found he really is an undiscovered species as Cassie and her new human treasure-seeking frenemy suspect, he could have moved out of the frying pan and into a fire - or tank - just as deadly.
Bit of a friendship and trust story, eco-tale, treasure seeking and even an escape plot. We get Blue and Cassie telling their sides of the story, with Blue nicely conveying how a fish might view the human world. And Cassie being the moral heart.
Enjoyed it, not too preachy, lots of good interplay between Cassie and her friends/dad, it felt like Free Willy or similar water-animal stories.
For ages 9-13.
With thanks to the publisher for providing a review copy.
Review of advance copy received from Publisher
I picked this advance copy out of the arc box because of the comp: "think Remarkably Bright Creatures for children!" and it's such a great comparison because you have a thinking, interactive creature, Marcellus the octopus and Blue the maybe missing link of fish, respectively, and while the premise may seem a tad hokey at first glance, the characters and friendship are written everyway but that.
Blue is a mystery. He has big eyes like a deep-sea denizen, he has pectoral fins that grip rocks and help him walk. And he's trapped in a cage of seaweed that brings him closer to the surface, and closer to Cassie.
Cassie helps her dad out at a local aquarium where he's the aquarist. She's a treasure-hunting beachcomber on the trail of a diamond necklace, and she's terrified of the ocean. I was expecting a little more of the friendship building between Blue and Cassie, and instead it's between Cassie and Mystery Boy who has the same metal detector as Cassie but the exact opposite personality to her careful control. Their friendship is so sweet and seeing how the characters grow, learn, and lean on each other makes for the perfect arc.
Highly recommend for readers who love animals, especially ocean creatures, and combing the beach for treasures.
Blue is a mystery. He has big eyes like a deep-sea denizen, he has pectoral fins that grip rocks and help him walk. And he's trapped in a cage of seaweed that brings him closer to the surface, and closer to Cassie.
Cassie helps her dad out at a local aquarium where he's the aquarist. She's a treasure-hunting beachcomber on the trail of a diamond necklace, and she's terrified of the ocean. I was expecting a little more of the friendship building between Blue and Cassie, and instead it's between Cassie and Mystery Boy who has the same metal detector as Cassie but the exact opposite personality to her careful control. Their friendship is so sweet and seeing how the characters grow, learn, and lean on each other makes for the perfect arc.
Highly recommend for readers who love animals, especially ocean creatures, and combing the beach for treasures.
November 27, 2025
This is simply the loveliest book—clever, touching and literally laugh out loud funny in parts. Everything about it is delightful and five stars aren’t enough.
December 5, 2025
Digital ARC. Middle grade children’s book. Adventure and coming of age story.
Review of advance copy received from Publisher
Review forthcoming. A middle grade story told to perfection with humor and so much humanity.
Review of advance copy received from Publisher
Review to come.
Absorbing, fun, and wonderfully unique!
Absorbing, fun, and wonderfully unique!
Displaying 1 - 7 of 7 reviews