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X-rays can kill cancer cells and save lives when administered properly. They can also kill people when things go wrong – a fact learned the hard way by retired FBI agent Cliff Knowles. Hired to unravel the cause of some mysterious overdoses, he gets too close to the truth and finds his own life on the line. Inspired by actual cases he worked as an FBI agent in Silicon Valley, the author weaves an absorbing tale of greed, technology, and terrorism in this high-tech legal thriller. After reading Fatal Dose you’ll never look at an X-ray machine the same way. Fatal Dose follows geocaching FBI agent Cliff Knowles in the third riveting installment of the popular Cliff Knowles Mysteries series.

287 pages, Kindle Edition

First published September 13, 2013

13 people are currently reading
68 people want to read

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Russell Atkinson

17 books40 followers

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Displaying 1 - 10 of 10 reviews
Profile Image for Stewart.
115 reviews
March 23, 2025
I enjoyed the first two books enough to keep reading the series, but this one isn't great. There are element's of Atkinson's writing that need to get better and there is no sign of progress (although we are least getting a bit less of the excessive FBI process explanations). Unfortunately, the real issue here is the "mystery" which is to say there isn't one. The "bad guy" becomes obvious early on and then yup, he just turns out to be the bad guy. Also, Cliff is becoming more shallow and less likeable.
Profile Image for Mystereity Reviews.
778 reviews50 followers
February 6, 2017
See my full review and more at Mystereity Reviews

PI Cliff Knowles, a former FBI special agent, is hired by Xlectrix to investigate several incidents with their latest cancer radiation machine, the Lilac 4. After several patients receive an overdose of radiation, including two who later died, the company is concerned that someone has done the impossible and figured out how to hack the machines - which were engineered to be tamper-proof. When his investigation leads to threats on his life, Cliff finds himself in a race against time to track down a vindictive and sadistic man bent on revenge.

Fatal Dose is a great read, with a chilling plot that touches on a primal fear everyone can relate to; being very sick, very scared, and the vulnerability of being at the mercy of a machine - or, even more frightening, having your child at the mercy of a machine. Eek!

The exciting plot had several cases seemingly unconnected to each other that were woven seamlessly in the story; the shooting of a police officer, a bank robbery, a Jewish center bombing, and the x-ray machine sabotage. I love watching the cases unfold; although there's a lot going on, it's very easy to follow and the quick pace keeps the story moving right up to the exciting and grimly satisfying ending.

Having already read Behead Me, a later book in this series, I liked seeing how Cliff and future wife Ellen first met, and their geocaching adventure with Ellen's niece, Ashley added a fun and heartwarming moment lightened the book considerably. Very cute!

Overall, Fatal Dose is a chilling and terrifyingly realistic thriller that will stay with you for a very long time. This is a must read series for fans of thrillers and procedurals, and especially geocachers.
Profile Image for Nikki.
4 reviews
August 10, 2025
Kept me on the edge of my seat

I've never read anything from this author before but I love his writing style and he's definitely on my list now. I've already downloaded all the other books in this series and can't wait to start from the beginning.
Profile Image for Randy.
277 reviews3 followers
October 24, 2014
I heard about this book because it had some geocaching in it. I have the kindle version and found myself going between the kindle and my phone. The story line was suspenseful and interesting, although it could have used more geocaching. I get a bit perturbed by people getting into fights, car accidents, etc. and the timeline gets super compressed into complete recovery in a couple days. The 'larger than life' characters are understandable and the plot must go on. It was an interesting look into a dual role, that of a lawyer and that of a retired FBI agent. I picked up the kindle version of another of the author's books, "Held For Ransom" when the main character Knowles was still at the FBI. In addition, I heard the fourth book has more geocaching so yes, I will be picking that one up too, soon enough.
251 reviews3 followers
January 16, 2014
Another great read by this author

I enjoy reading books that have repeating characters in them. The Cliff Knowles series is not one to be missed! With every book the main character Cliff is developed even better. I thought when I first started on the book that I might have to jump ship because some of the technical computer angles seemed to be way over my head. However just in the course of the plot of the book it became clear and concise. i have downloaded yet another one in the series by this author and I'm looking forward to seeing what wild ride that one will be.
Profile Image for Becky.
417 reviews10 followers
August 10, 2014
Russell Atkinson leads the reader on another thrilling crime fighting adventure with his main character, Cliff Knowles, on an unforgettable quest to "get his man". Fatal Dose is the third in a series of books. Set again in Silicon Valley with a high tech slant, Mr. Atkinson develops an enthralling tale that cleverly weaves together several strands into a more than satisfying conclusion. I recommend this book to everyone who enjoys detective stories, mysteries, thrillers, and readers of a series of books.
Profile Image for Francisco Moraes.
35 reviews
December 3, 2013
I have read the other books from the author and so I was thrilled when I found there was a new book.

Once I finished my other reading, I finally started reading this and it didn't disappoint me. It was an entertaining read and just as good as Cached Out.
411 reviews15 followers
July 16, 2015
Found this series via some caching friends, and although there isn't as much geocaching within this book, it is still an enjoyable read. Characters are very believable, and sadly so are the situations. A good mystery that kept me reading page after page!
Profile Image for QuesterMark.
94 reviews
April 11, 2016
Third time's a charm

These Cliff Knowles books keep getting better and better! Just the right amount of action and suspense. And the author is good at determining how to gloss over boring stuff without omitting details.
Profile Image for Russell Atkinson.
Author 17 books40 followers
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August 2, 2015
I am the author. My rating/review is only for the purpose of adding the book. I'll delete it when other ratings and reviews appear.
This entire review has been hidden because of spoilers.
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