Countdown: A Post-Apocalyptic Survival Thriller

Code Umbra #1

by Millie Copper

370 pages, Kindle Edition

Published April 28, 2026

About the author

Click here to download your FREE copy of Wyoming Refuge.

Millie Copper, writer of Cozy Apocalyptic Fiction and preparedness mentor, was born in Nebraska but never lived there. Her parents fully embraced wanderlust and moved regularly, giving her an advantage of being from nowhere and everywhere.

Millie Copper lives in the wilds of Wyoming with her husband and young son, tending chickens and attempting a food forest on their small homestead. After living off the grid for several years, they've recently gone back on the grid. Four adult daughters, three sons-in-law, and five grandchildren round out the family.

Since 2009, Millie has authored articles on traditional foods, alternative health, homesteading, and preparedness-many times all within the same piece. Millie has penned seven nonfiction, traditional food focused books, sharing how, with a little creativity, anyone can transition to a real foods diet without overwhelming their food budget.

The twelve-installment Havoc in Wyoming and six-installment Montana Mayhem Christian Post-Apocalyptic fiction series use her homesteading, off-the-grid, and preparedness lifestyle as a guide. The adventures continue with the upcoming Dakota Destruction series.

Reviews

[Matt Egan · Rating 5 out of 5]

Cooper joins the apocalyptic big leagues!

Countdown, book 1 in the Code Umbra series chronicles the period immediately preceding the passage of a massive near earth object between the earth and the moon, expected to cause untold chaos on a global scale. Tessa Courtland formerly worked for a conglomerate that tracked objects in the Solar system. A mysterious phone call with the phrase "Code Umbra" changes everything. Tessa suddenly finds herself, her family, friends and co-workers all in mortal danger from her former employer. The book is, simply put, phenomenal! Even with the destruction not really occurring yet, Cooper manages to torque up the tension with her skilled storytelling. This is a standout book for me this year, the world building is stellar, no pun intended. The set up for book 2 leads me to believe it will be a wild ride, A ride I'm eagerly waiting for! Overall, 5/5 stars, highly recommended for fans of apocalyptic survival thrillers and immaculately plotted conspiracy thrillers, or just thrillers in general. The writing is sufficiently excellent to attract readers who might not normally even read the genre!

[Cody · Rating 4 out of 5]

Really good

For the 1st book of this series, the asteroid is more of an asterisk. The real story is Tessa and Erin. Lot's of exciting edge of your seat goings on.
Looking forward to book 2.

[Rick Allen · Rating 5 out of 5]

A great start for a new series. The set-up is an astronomer who used to work for a shadowy organization that paid her to set up a system tracking asteroids and meteors that might threaten the Earth. Sounds noble, but this outfit actually wants to leverage world-changing events for their own benefit. As the book opens, the astronomer gets yanked back into this group to verify that their hoped-for scenario is coming true: an asteroid is on its way to devastate Earth. And while they work behind the scenes to feather their own nests, they show no compunction in killing anyone that might give away the news before they're ready. The astronomer has to run for her life and to protect her family.
I'm excited to see where the series goes after this, how the main character and her family gets on in the new world after the devastation. The writing is very good, and I felt the characters' struggles.

[Graeme Williams · Rating 5 out of 5]

Countdown is a tense and fast-moving post-apocalyptic survival thriller that centers on urgency, resilience, and the human instinct to endure against overwhelming odds. Millie Copper leans into the genre’s core strength, high-stakes decision-making under pressure, while maintaining a strong emotional undercurrent that keeps the narrative grounded.

The story builds momentum through escalating threats and limited time, forcing its characters into impossible choices where survival often comes at a cost. The pacing is sharp and deliberate, creating a sustained sense of tension that mirrors the relentless countdown implied in the title.

This is a gripping survival-focused thriller that emphasizes atmosphere, urgency, and the psychological strain of navigating a collapsing world.

[Cristy Robinson · Rating 5 out of 5]

terrifyingly real possibility mixed with great characters

Millie Copper has done it again! Kept me up at night, and making me spend a weekend reading. Code Umbra series is off to a great start and I can’t wait to dive into book 2!
I connect to Tessa. As a mom, I’d do anything for my kids and she is a great Mama Bear. But I am also looking forward to watching her daughter Kylie grow and change over the series, as well as her friendship with Erin develop. Marco is the perfect second / husband to Tessa, steady and trusting, yet capable.
In all, a great series starter!

[Courtney Santos · Rating 5 out of 5]

I love Millie Coppers writing. This book did start off as a slow burn but the payoff was so worth it! If you love complex characters and heart pounding situations this is it for you. This is a new situation for me under this genre and that’s saying something. I can’t wait for the next one and also recommend her other books as well!

[Nancy Parkinson · Rating 5 out of 5]

Another fantastic series In the making!

Millie has found a way To be able to write these series and keep people interested. She must practically LIVE the main characters' lives because she picks up on the little nuances she wouldn't normally.
And, her writing style just fit together, like a hand in a glove, with her imagination!

[Sam · Rating 5 out of 5]

This was really brilliant! I slightly different type of apocalyptic adventure from this writer & wow what a pleasure it was to read! Great pace, good tension & a super interesting plot! I do recommend!

[Larissa Newman · Rating 5 out of 5]

So much going on!

I love all of Millie’s books and this one definitely did not disappoint! There’s so much going on and you just can’t stop reading because you have to know what’s coming and if they’re going to be okay. I am ready for the next book in this series!

[Regina Hay · Rating 5 out of 5]

fantastic story!

Here is a thought provoking take on apocalyptic story lines. Plenty of action and the characters were good. Some copy editing was in order. I spotted quite a few typos. But I’m definitely looking forward to the next book.

[Jennifer · Rating 5 out of 5]

Such a great book! I couldn’t put it down. I can’t wait for the next one to come out. I want to know what happens next.

I received an ARC copy from the author and all opinions are my own.

[Leslie · Rating 5 out of 5]

Loved this book

This story was great! It kept my heart pounding! I can't wait for the next book. I love this author's books, try out some of her other series

[Kathaleen A. Gregorich · Rating 5 out of 5]

Great thriller/sci fi

Never read Millie Copper before! What a great author! Story was well written, fast pace and a great story!!!...think I have found my new favorite author!

[t r · Rating 5 out of 5]

This is unlike any other post apocalyptic thriller I have read. This was a bit of a slow burn and I was unsure of what I'd gotten myself into. I'm glad I kept reading. After a few chapters I was hooked and couldn't put it down. If you're into nail biting thrillers and government shenanigans, this is for you. Oh, and the over zealous reporter has his moment too.
I'm a book reviewer for this book and I am leaving this review voluntarily