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InvestiGators #9

InvestiGators: Case Files

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A special interactive installment of InvestiGators, a bestselling early reader series about a super spy alligator duo that has sold more than 3 million books!

Special agents Mango and Brash are back again, and this time they’ll be asking their readers for help in cracking the case! The gators have been given a brand new add-on for their V.E.S.T.s to help with gathering evidence and making sense of clues – the G.R.I.D. (Gator Reasoning, Inquiry, Deduction) – and with that powerful tool in hand, kids can follow along as they solve six brand-new mysteries! Featuring plenty of familiar faces from investigations past, as well as a few brand new suspects, Mango and Brash and YOU (the reader) will get to the bottom of cases big and small!

208 pages, Hardcover

Published September 9, 2025

49 people are currently reading
146 people want to read

About the author

John Patrick Green

67 books375 followers
John Green grew up on Long Island and has worked in New York City ever since graduating from School of Visual Arts for Graphic Design in 1997. He was the comics consultant for Disney Adventures magazine, and in addition to Disney has written, illustrated, or otherwise worked on comics for Nickelodeon, Dreamworks, Scholastic, DC Comics, and First Second Books. When not drawing comics John creates artwork for video games, such as Emerald City Confidential, Puzzle Bots, and Nearly Departed. See more of John's work at www.johngreenart.com.

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5 stars
102 (58%)
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26 (14%)
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Displaying 1 - 29 of 41 reviews
Profile Image for Mindy Steele.
56 reviews2 followers
October 10, 2025
InvestiGators: Case Files
If you’re a fan of the series, you’re in for a real treat, not one, but SIX cases to solve!

These cases are bound to be swamp-licated, so they Mango and Brash ask you to grab some paper and pencils to fill out your clue book! They use a fancy new GRID technique finding sets of three clues and three suspects. Plus they discuss what red herrings are and how to go back and look through clues!

These gators always brings the perpetrators to jaws-tice!

From a parent view: my son devoured this. He had his notes written and was proud he got 3 out of the 6 cases correct. He read the book in one sitting and asked for more books like this in the future. I will definitely purchase the hardcover when released! I love when books engage and pique interest.

From an educator view: when a books brings this much curiosity and makes you question and wonder, it’s a winner. It doesn’t matter if we were correct. I will definitely recommend this to my students!

From a child’s view (9 years old): “I LOVED this! It’s was so much fun! I loved solving the mysteries and that they built upon one another!”

Thanks @NetGalley and @FirstSecondBooks for the Advanced Digital Copy
Profile Image for Dayle (the literary llama).
1,565 reviews187 followers
August 13, 2025
A 7 y/o’s review:

Me: Do you know what star ratings are?
7: … ummmm, oh! Is it like those things that are ummmm, that people, ummm… they’re on books with stars that people say about the book?
Me: yes! You get to give this book stars.
7: I GET TO?! And then people will know what stars I gave it?
Me: yup! So how many, one to five, stars do you give the new InvestiGators?
7: FIVE! It’s so good!

A further paraphrased review from the kiddo…

Investigators is one of his all time favorite series. He loves that they are “big” books ‘cause it keeps him entertained for longer. Very important for a kid that reads ravenously. They’re worth it!

Loves that there are multiple stories/cases within Case Files. Not his favorite among the whole series BUT basically ties for second with all the others. He couldn’t think of a thing he’d change and his favorite part was when the simulator came to life. And his favorite character is Mango (needed to make sure that was mentioned somewhere in the review).

Overall, it was another winner and 7 hopes that the author will know how much he loves this series.

* We received a free ecopy from the publisher
Profile Image for Christina Getrost.
2,435 reviews77 followers
October 2, 2025
Newest in the series of funny silly punnerific graphic novels about two alligator spies. I love the premise for this one, it is a collection of six cases set up for the reader to solve along with Mango and Brash. So the story stops partway through, after the gators have collected 3 or more clues in their "G.R.I.D."s (which stands for "Gator Reasoning, Inquiry, and Deduction"--teaching inductive reasoning and mystery solving skills through a GN, I love it!), and directs readers to go back to certain pages and go over the clues before proceeding, and see if they can solve it themselves. I personally didn't get it right all of the time, it was actually kinda tricky! But a whole lot of fun. Pulls in characters from other books in the series. Too cute.
Profile Image for Brooke.
342 reviews6 followers
August 1, 2025
Thank you to Macmillan Kids for an eARC of this graphic novel. This was a great graphic novel to get the whole family involved! My kids (8 and 5) absolutely loved the G.R.I.D system that created breaks in each story to present the clues so far. They would guess which clue was most important, then keep modifying their theories through each Check-In. My kids are big readers already, but they were so engaged through this whole graphic novel. With the signature InvestiGators wit and puns, this was a hit all around. I even got requests to read throughout the day and not just at bedtime. Highly recommend to read together.
Profile Image for Leila.
15 reviews
November 29, 2025
Love this series!!!! This time they have 6 cases to solve! My favorite one was probably where they were at the amusement park :)
Profile Image for Brandon.
2 reviews2 followers
January 2, 2026
Really good,about 5 mysteries,3 clues,choose wisely
Profile Image for Olivia.
3,769 reviews99 followers
Read
September 10, 2025
See my full review here: http://yabookscentral.com/investigato...

INVESTIGATORS: CASE FILES is a fun new installment in this comedic graphic novel detective series. This latest features six different cases which agents Mango and Bash will need to solve. Using their top-notch detective skills and G.R.I.D., they will seek out the whodunnit behind each mystery.

What I loved: This is a clever new book for children who appreciate shorter stories. Each mystery feels complete and presents a whole case, with lots of memorable characters from the past (and some new faces). Like all books in this series, there is some serious detective work - but also loads of humor throughout with silly acronyms, ridiculous assumptions, and red herrings. While many jokes are perfect for the intended audience, there are some that are quite clever and may need additional context, but it adds to the overall fun of the story with a bit of thought needed to understand all the humor.

The illustrations are fantastic with lots of details and bright colors. The speech bubbles are easy to attribute, and the panels are organized well so that young readers can easily follow along and understand what is happening. A lot of the story happens in the images, and this is perfect for independent readers who are gaining confidence. They can use the illustrations for context clues as they smoothly follow along with the story. The illustrations spread out the text, so they can zoom through the book.

Final verdict: With smart humor and memorable characters, INVESTIGATORS: CASE FILES is a fantastic new installment in a charming graphic novel series. Smaller cases make this a unique book in the series that is great for independent readers gaining confidence as well as current fans of the series! Highly recommend this one for children who love to solve mysteries and laugh along the way.

Please note that I received an ARC. All opinions are my own.
Profile Image for *ੈ✩‧₊˚Sassy Little Hippy˚₊‧✩ ੈ*.
239 reviews14 followers
September 2, 2025
4.8 ⭐️

The InvestiGators are back in action with six brand-new cases to crack! But this time, Mango and Brash aren’t relying only on their detective skills and memory. They’ve leveled up with the handy-dandy G.R.I.D., a clever device that helps them track clues along the way. Even better? They invite us—the readers—to step right into the mystery with them. It takes a sharp eye (and maybe a bit of silliness) to catch these sneaky criminals!

From My 11-Year-Old:
"This book has the same charm as the original series. It’s fun, funny, and the cases were both interesting and challenging. I felt like the whole world was depending on me to help solve these six cases, and I loved being part of the InvestiGator Team A. I can’t wait for the next book in the series!"

From the Parent Perspective:
From a reading standpoint, this book is perfect for ages 7 and up. From a problem-solving standpoint, some cases are surprisingly challenging and really reward kids (and parents!) who have an eye for detail. We especially enjoyed the subtle clues sprinkled throughout, paired with the goofy, over-the-top storytelling. These books are always a family favorite to read together. (For the record, I’m usually Brash, and my son is Mango.) It’s clever, interactive, and laugh-out-loud fun for the whole family.

Thanks to NetGalley, First Second Books, John Patrick Green & Steve Behling for providing us with a complimentary ARC to review!
Profile Image for Darla.
4,884 reviews1,262 followers
November 29, 2025
There is a new team member helping the InvestiGators -- it's YOU!

This ninth InvestiGator installment is interactive. Brash has developed a new system called G.R.I.D. (Gator Reasoning, Inquiry, and Deduction.

Here's where you come in:

🔍As clues are discovered, they are entered into the G.R.I.D. After each row of three boxes is filled, Mango and Brash have a short meeting with their team (including the reader).
🎣Red Herrings are emiminated in three rounds. Leave it to the production team to include a fox named Fred Herring.
🐊Mango and Brash start with 'The Missing Mayo Mystery,' and continue on to solve 'The Baking -Soda Boggler,' 'The Wandering Wugget Mystery,' 'The Carnival Conumdrm,' 'The Hologram Holo-Headache,' and 'The Electric Enigma Encounter --' with your help.
6️⃣Each of the six mystery 'chapters' will give you chance to hone your craft at detecting and at the end of the book you can practice drawing Fred Herring.🦊
📚 If you have been following the series, this one will not disappoint. The punny word play is at its best including Matt Ress's Mattresses, Mattresses, owned by Matt Ress. Put your thinking cap on and get ready!

Can YOU crack the case?🐊
Profile Image for Becky B.
9,387 reviews186 followers
January 20, 2026
The InvestiGators invite readers to help them solve 6 cases. They gather clues with you, then use G.R.I.D. (Gator Reasoning Inquiry and Deduction) to figure out the culprit. First figure out who took the jar of mayo containing passwords off the General Inspector’s desk. Then find out who stole the baking soda at the lab and prevented the volcanoes from working. Then figure out who is taking cameraman Cameron’s Wuggets. Next track down who stole the tickets at the carnival. Then figure out what is making the hologram machine at SUIT HQ malfunction. And finally track down who is shutting down power all over town.

I like how this encourages readers to get involved. If you are observant it is fairly easy to crack the cases before Mango and Brash. But it does take careful reading and looking at the illustrations. A very fun addition to the InvestiGators series.

Notes on content:
Language: None
Sexual content: None
Violence: None
Ethnic diversity: The people appear to come from a variety of ethnic backgrounds but most characters are animals or robots.
LGBTQ+ content: None specified.
Other: None
Author 6 books2 followers
September 21, 2025
There is something so intoxicatingly delightful about the InvestiGators series.

In this latest book, special agents Mango and Brash earn a new add-on for their V.E.S.T.s to help them gather evidence - the G.R.I.D, the Gator Reasoning, Inquiry, Deduction add-on.

Even with the G.R.I.D., these two need all the help they can get in solving a fresh slate of mysteries. They'll need their constant reader's keen eyes to solve these cases. Our goofy gators encounter such clues as a handprint in a mush of mayonnaise, a potato filled with baking soda, and suspects like a floating eye-ball butler and a rooster with a Ph.D.

I love reading books from this series with my kids. They eagerly follow the clues, noticing the details that our special agents need to solve the case.

I highly recommend this latest adventure.

Thank you to NetGalley and First Second Books for the advance copy. All opinions are my own.
Profile Image for Rachel.
1,021 reviews17 followers
April 21, 2025
*I received a free ARC from the publisher through NetGalley in exchange for my honest review*

I love the InvestiGators series and am always excited when a new book from the series is released. This book is a little different in that it is giving the reader the opportunity to solve the cases alongside Mango and Brash. What I really liked about the book is formatted that it helps walk readers through how to solve the crimes, identify important clues, and introduces them to the idea of a red herring. I also liked that readers are encouraged to look back through the story (with specific page numbers noted) to review what they read. The mysteries are just as funny and silly as those from the full-length books and are sure to keep younger readers entertained. I hope the author puts out more of these types of books in the future!
Profile Image for Nikki Ruzick.
129 reviews7 followers
July 6, 2025
InvestiGators: Case Files #9 is another hilarious and action-packed addition to the series that my students are going to absolutely love! Mango and Brash are back, diving into six different cases, and the interactive format really sets this one apart.

The G.R.I.D. machine is a clever tool for organizing clues, and the built-in references that send readers back to earlier pages make the experience both engaging and fun. It adds an extra layer of detective work that will definitely appeal to young readers.

The illustrations are vibrant and full of energy, and the humor ~ even for adults ~ is laugh-out-loud funny at times. I found myself chuckling more than once! I can’t wait to add this to our classroom collection, I know it’s going to be a hit.

Perfect for fans of graphic novels, humor, and all things quirky and clever!

Thank you, NetGalley and First Second Books for the ARC.
Profile Image for Heather.
140 reviews3 followers
August 8, 2025
IvestiGators: Case Files is book nine in The InvestiGators Series by John Patrick Green. It is an interactive book where kids get to help solve the crime.

Special Agents Mango and Brash need YOUR help to use their new G.R.I.D. system to solve crimes and close cases! 

All of the InvestiGators books are a blast to read with my six-year-old son. He enjoys reading and re-reading the books, and this one was no exception. InvestiGators: Case Files is filled with humor that will keep both kids and grown-ups entertained! The interactive portion of the book turns little ones into investigators, making them feel like they are truly a part of the story. Here’s what my son had to say about this book: “It was really funny, and I liked that Fred Herring was a red herring.” 

Thank you, First Second Books, for providing this book for review consideration via NetGalley. All opinions are my own.
Profile Image for Lauren.
329 reviews52 followers
August 25, 2025
My InvestiGators superfans squealed in delight when we got the approval to read the latest installment in this beloved series. My kiddos (7.5 and 9) both said Case Files gets five glowing stars. We have read the previous books countless times and they never cease to be tickled by Mango and Brash’s adventures and hijinks.

They kept saying over and over while reading was how much fun that had BEING an InvestiGator and getting to be super sleuths, though they were grateful not to have to travel via toilet to solve these cases! They successfully completed each case file and really loved the different interactive features, especially the look and find element in the final case.

My bookworms said this might be their new favorite in the series and they can’t wait to add this book to our InvestiGators and Agents of S.U.I.T. collection.
Profile Image for Pam.
9,954 reviews56 followers
August 10, 2025
Graphic Novel
I received an electronic ARC from First Second Books through NetGalley.
I like the way Green changes the formula and challenges readers to be investigators along with Brash and Mango. We are provided with six short cases rather one long one. Mango introduces a new problem solving tool, the G.R.I.D, and uses it for all six incidents. Readers can study the scenes and make their own inferences. They can also study the information placed in the G.R.I.D. and see if they come up with the same solution as the Investigators. The author maintains the humor style from the other books and lets readers enjoy the ridiculousness along with the characters. Could be a fun book to read one case at a time to teach deductive reasoning and observation.
398 reviews11 followers
September 7, 2025
Reader favorites Mango and Brash return in a new INVESTIGATORS book with a fun format twist. This installment includes six short interactive mysteries that invite readers to collect clues and solve the cases along with Mango and Brash. Along with the signature word play, colorful artwork, and humorous banter between characters that readers have come to expect from this series, this new format encourages reader engagement and interaction as it builds critical thinking and problem solving skills. As a school librarian, I know our readers will pick this one up thinking it’s like the other INVESTIGATORS and AGENTS OF S.U.I.T. books but I think they’ll be pleasantly surprised by the interactive format. Another INVESTIGATORS win!
92 reviews2 followers
July 20, 2025
The gator detectives are back—but this time, you’re part of the team.

In this interactive spinoff, Mango and Brash take a break from their usual capers to guide readers through a series of six mini whodunits. With a clue-finding format that encourages critical thinking, re-reading, and deduction, Case Files turns passive reading into active problem-solving.

The art by Chris Fenoglio captures the series’ signature zany charm, while the puzzles offer just enough challenge to keep minds engaged—and chuckles flowing.

It is wacky, clever, and brilliantly hands-on—Case Files is a gator-grade win.
Profile Image for Larissa.
949 reviews2 followers
August 15, 2025
Investigators did it again. I love this idea of mini stories and readers who enjoy solving their own mysteries are going to love being able to work alongside Mango and Brash to help them solve crimes. Each story is the perfect length to allow readers to gather clues and be engaged enough that they are excited to solve the mystery. I also love how the final case ties into the previous ones. This honestly is a genius way to continue this series and I know readers are going to love it just as much as I did.
Thank you to First Second Books and Netgalley for allowing me to read an advance copy of this title.
Profile Image for Stephanie Rivera.
383 reviews
June 21, 2025
Another great installment of the InvestiGators series and this one was a little different since it was a 6 mini cases that interacted with each other than just one case that Mango & Brash work on through the whole book. It was fun and interactive since they give you a list of 3 clues and 3 suspects for the reader to help figure out who the culprit is. The illustrations were great and the story was easy to follow for young readers.
Thanks to First Second and Netgalley for the complimentary copy of this book. All opinions in this review are my own.
117 reviews1 follower
January 14, 2026
I had a 13-year old neighbor read and review this book:
Another great book from the Investigators series! I loved the ‘Grid’ Gator Reasoning Inquiry Deduction tool and thought it was cool how they used it to take them through the steps to solve crimes. It gave me an idea of how to solve a crime.The story was about 3 or 4 different crimes that animals committed and how they solved them using the Grid. The book was very interesting, a little different from others in the series, but still very good.
54 reviews
June 28, 2025
Thank you to NetGalley and First Second Books for the digital ARC.

The InvestiGators are back with an exciting new adventure that will have kids cheering on every page. I loved how interactive this book is, encouraging young readers to grab a pen, paper, and their detective hats to fully immerse themselves in the experience. I can also see myself purchasing several copies for our school library.
Profile Image for Mara K..
262 reviews
July 19, 2025
i did'nt like it as much as the other books, but it was still ok.
i enjoyed the different mysterios, but the clue thing made it a little hard to follow.
maybe it would have been funner if i was reading it as paper, so i could flip through better.
i also wish the golfer ended up having his own big mystery at the end, since he was always doing suspicious things.
but pretty good.
i liked it
thanks to netgalley and the publisher for letting me read it in advance!
Profile Image for Dark Reader.
487 reviews18 followers
August 15, 2025
We love the InvestiGators series, and this is a great addition! Unlike the rest of the series, this is a group of six shorter cases that the reader can help solve. My son really enjoyed reading this!

Thank you to the publisher and Netgalley for a review copy!
Profile Image for Kelly.
66 reviews
September 16, 2025
My kiddo and I always love reading these books together and this one was no different. Perfect for little mystery lovers puzzle solvers! I received an eARC of this book in exchange for an honest review
Profile Image for Emily (The Litertarian).
338 reviews30 followers
November 21, 2025
My two young sons and I LOVED this book. The way they studied the scenes with clues was so adorable, and kept them entirely engaged. I loved that there were several cases and we could look forward to a new one each day. We are certainly buying this one for our at home collection!!
Profile Image for Eric Smith.
57 reviews
December 28, 2025
A funny and entertaining series of kids graphic novels that is also very interactive, having the reader try and solve the mystery in each story. I read this with my 8-y.o. son and he was able to solve every one!
Displaying 1 - 29 of 41 reviews

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