Learn more
These promotions will be applied to this item:
Some promotions may be combined; others are not eligible to be combined with other offers. For details, please see the Terms & Conditions associated with these promotions.
Your Memberships & Subscriptions

Download the free Kindle app and start reading Kindle books instantly on your smartphone, tablet, or computer - no Kindle device required.
Read instantly on your browser with Kindle for Web.
Using your mobile phone camera - scan the code below and download the Kindle app.
Neptune-Six (Adam Knight Thrillers Book 4) Kindle Edition
In the small South American nation of Vincidoria, a rebellion clings to survival. Isabella Rodriguez, its beloved leader, becomes the target of the country’s despotic President and his ruthless death squads, forcing her to request asylum from the United States government.
With the CIA rescue operation of Rodriguez in tatters, the elusive Penumbra Division takes command of the extraction and deploys their top operative—Adam Knight.
Arriving in Vincidoria with no contacts and surrounded by enemies, Knight faces an adversary more deadly than he anticipated—the Oscura, Vincidoria’s secret police. Dedicated to crushing dissent with brutal efficiency, the Oscura pose a threat not just to the rebels but to any foreign operatives.
The simple extraction rapidly descends into chaos as Knight stumbles upon a web of dark forces with stakes far beyond Vincidoria’s borders. Can he safeguard the world against the hidden enemy, or will he be destined to disappear into the South American jungle forever?
If the high-octane narratives of Tom Clancy, Lee Child, Robert Ludlum, Vince Flynn, and Ian Fleming keep you turning pages late into the night, then prepare to be engrossed by the world of Adam Knight.
- LanguageEnglish
- Publication dateMarch 9, 2025
- File size6.8 MB
Shop this series
See full series- Kindle Price:$10.97By placing your order, you're purchasing a license to the content and you agree to the Kindle Store Terms of Use.
- Kindle Price:$15.96By placing your order, you're purchasing a license to the content and you agree to the Kindle Store Terms of Use.
Shop this series
This option includes 3 books.
This option includes 4 books.
Customers also bought or read
- Blaze Returns: Axel Blaze Crime Action Thriller Book 1 (Axel Blaze Thriller)Kindle Edition$3.99$3.99
- RISKY MISSION an unstoppable crime thriller with a shocking twist (Frank Doy Book 1)Kindle Edition$2.99$2.99
Customers who bought this item also bought
Product details
- ASIN : B0DXCNPTTL
- Accessibility : Learn more
- Publication date : March 9, 2025
- Language : English
- File size : 6.8 MB
- Simultaneous device usage : Unlimited
- Screen Reader : Supported
- Enhanced typesetting : Enabled
- X-Ray : Not Enabled
- Word Wise : Enabled
- Print length : 370 pages
- Page Flip : Enabled
- Book 4 of 4 : Adam Knight Thrillers
- Best Sellers Rank: #80,570 in Kindle Store (See Top 100 in Kindle Store)
- #455 in Assassination Thrillers (Kindle Store)
- #579 in Military Thrillers (Kindle Store)
- #595 in Espionage Thrillers (Books)
- Customer Reviews:
About the author

My passion for storytelling began as a child, sparked by the exploits of James Bond and the action films of the 80s and 90s. As I grew, I found inspiration in the literary works of Tom Clancy, Michael Crichton, and Lee Child.
In 2024, I released my debut novel, Shadow Operative, the first in the Adam Knight Thriller series. What began as a single book has since grown into a fast-paced, globe-trotting series spanning four novels...and counting. In June 2025, I’ll be launching a spin-off set in the same universe centering on Penumbra Division, starting with The Last Operator.
In early 2025, I signed a multibook deal with Boldwood Books to launch a brand-new series featuring Dane Winter, an elite ex-soldier turned freelance operative. The first book is set for release in October.
Off the page, I’m a devoted husband and proud father to a son and daughter. Without them, none of this would be possible.
Customer reviews
Customer Reviews, including Product Star Ratings help customers to learn more about the product and decide whether it is the right product for them.
To calculate the overall star rating and percentage breakdown by star, we don’t use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyzed reviews to verify trustworthiness.
Learn more how customers reviews work on AmazonTop reviews from the United States
There was a problem filtering reviews. Please reload the page.
- Reviewed in the United States on May 28, 2025Format: KindleAdam Knight (or Fisher in this case) is headed to Venezuela to bring the head of a rebellion to safety in the US. What he's unaware of is that the request for sanctuary came from the head's spouse. She would never leave the people who trusted her to remove the current Venezuelan President and corrupt government and law enforcement. She knows a lot more than the US government thinks.
- Reviewed in the United States on March 10, 2025Format: KindleSolid action/thriller novel by Sam Cogley. This is the 4th book in the Adam Knight series. Knight is sent on a clean-up mission to somewhere in South America to extract an asset which an earlier attempt failed at. Turns out the person to be "rescued" didn't ask -- her husband did for her as she was the leader & face of the revolution. Long story short: she doesn't want to go with Adam but gives him some priceless intel -- pictures of an advanced weapon stolen from Seattle. Knight gets back & is immediately sent to London to work with MI6 to protect the guidance system for the stolen weapon system. Add in some Middle East jihadist types & you have the recipe for a great action packed thriller.
- Reviewed in the United States on March 10, 2025Format: KindleI received an ARC through "Booksprout" and I am voluntarily leaving an honest review.
The story begins with a CIA agent attempting to help an Opposition leader escape from Vincidoria to the United States. A meet was schedule and things didn't go well. The CIA agent was captured by agents of Oscura.
The story then relates the actions that Knight took on a flight traveling from Los Angeles to New York. He discovered that the plane was hijacked while he was asleep. He then had to develop and perform a plan to take the hijackers out. Read how he was able to succeed. Upon arriving, he was then assigned a task to go to Vincidoria and extract the same opposition leader. Knight on arriving decided to go to the safe house where the CIA agent was to meet with the leader. As it turned out, the house was under watch by the Oscura and they attempted to capture Knight. In their attempt, Knight was able to escape. He then went to the police station to try and find information where Isabella, the opposition leader, might be. He then picked up a clue which eventually led him to a location where Isabella was once hiding.
Learning that she had gone in the jungle, Knight and a team from the opposition went to locate her. After fighting off several attacks, they discovered that Isabella had been captured. Follow the actions Knight took in order to free her. Knight eventually learned that Isabella did not want to leave, but she did give him information that she learned about, and this was the object known as Neptune Six.
Once Knight got back to the U.S.A., he was then sent to London to try and locate and destroy the item known as Neptune Six. He was teamed up with an MI6 agent Sarah Croft. In their travels they were captured and transported to an island location. This is where Neptune Six was located.
To discover what Neptune Six was, why Knight had the task to destroy and how he was able to accomplish it, then you need to read the book.
- Reviewed in the United States on May 14, 2025Format: KindleA well written perfectly paced story pulling you in from the start. This is just another mission that Knight was placed on to get to the bottom of something that was stolen. There was plenty of action going on to keep you turning the pages to keep your interest.
- Reviewed in the United States on March 9, 2025Format: KindleAdam Knight works for the secretive Penumbra Division. When the CIA fails the Penumbra Division takes over. There is catastrophic failure by the CIA in a small South American country leads down the path to nuclear destruction. From the amazon jungles to London to a secret island. Can Adam secure a freedom fighting rebel leader? Who can trust who will betray him? Can he stop a devastating blow to a major city? This is a well written novel with a phenomenal storyline complex and realistic. Adam is an operative that believable, realistic, skilled, and dedicated to helping just causes. He is willing to put his life on the line to save others. This is a well woven story that moves the reader through the novel at a very compelling pace.
- Reviewed in the United States on March 9, 2025Format: KindleI have loved every book in this series, and they keep getting better. In this episode, our hero takes us from the jungles of South America to London to an Island somewhere (no spoilers!). He solves one thing after another, but always seems to be a step behind…he definitely got more emotionally present in this book. By the end, I’m even more intrigued by the overall plot arc from all the books. Is the next one where we really are going to learn who is behind all the chaos? I can’t wait to find out!
I received a free copy of this book via Booksprout and am voluntarily leaving a review.
- Reviewed in the United States on March 9, 2025Format: KindleA mission that starts as a rescue to help salvage a rebel cause quickly gives way to a bigger and more frightening plan by people Knight wasn’t expecting. Not knowing who to trust he must figure out a way to stop, what could well become WWIII. Lots of intrigue and action that is played out in many stages. But Knight will stop at nothing to stop this evil plan. A great sequel in this addictive series.
I received a free copy of this book via Booksprout and am voluntarily leaving a review.
- Reviewed in the United States on March 9, 2025Format: KindleThis is the fourth of Cogley's fast-paced thrillers that I've read. If you like spy-type novels, then you should definitely give this series a try. The plots are full of twists and turns which keep you turning pages as fast as you can. The main character, Adam Knight is resourceful and cunning; you can't help but cheer for his success.
I received a free copy of this book via Booksprout and am voluntarily leaving a review.