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Agent 21 #3
Codebreaker
Secret agent Zak Darke is back for his third mission - and the stakes have never been higher.
An unknown bomber is conducting a terror campaign in London. After an explosion on the tube leaves someone dead, Zak and his team are brought in to try and work out how this terror cell operates - but clues are scarce and they have no idea where, or when, the bomber will strike next. A teenage boy, currently detained in a young offender's institute, claims he has the answer - but before Zak can question him, the boy is shot and falls into a coma. Will Zak be able to break the cipher before the bomber strikes again?
An unknown bomber is conducting a terror campaign in London. After an explosion on the tube leaves someone dead, Zak and his team are brought in to try and work out how this terror cell operates - but clues are scarce and they have no idea where, or when, the bomber will strike next. A teenage boy, currently detained in a young offender's institute, claims he has the answer - but before Zak can question him, the boy is shot and falls into a coma. Will Zak be able to break the cipher before the bomber strikes again?
320 pages, Paperback
First published February 28, 2013
62 people are currently reading
664 people want to read
About the author
Chris Ryan
342 books1,019 followersColin Armstrong (b. 1961), usually known by the pen-name Chris Ryan, is a British author, television presenter, security consultant and former Special Air Service sergeant.
After the publication of fellow patrol member Andy McNab's Bravo Two Zero in 1993, Ryan published his own account of his experiences during the Bravo Two Zero mission in 1995, entitled The One That Got Away. Since retiring from the British Army Ryan has published several fiction and non-fiction books, including Strike Back, which was subsequently adapted into a television series for Sky 1, and co-created the ITV action series Ultimate Force. He has also presented or appeared in numerous television documentaries connected to the military or law enforcement.
After the publication of fellow patrol member Andy McNab's Bravo Two Zero in 1993, Ryan published his own account of his experiences during the Bravo Two Zero mission in 1995, entitled The One That Got Away. Since retiring from the British Army Ryan has published several fiction and non-fiction books, including Strike Back, which was subsequently adapted into a television series for Sky 1, and co-created the ITV action series Ultimate Force. He has also presented or appeared in numerous television documentaries connected to the military or law enforcement.
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Displaying 1 - 30 of 45 reviews
May 16, 2018
Agent 21: Codebreaker is the third book in Chris Ryan’s Agent 21 series, and as with the first two books I found it to be an enjoyable quick read. In fact, this third book is easily my favourite of the first three books. If I’m being completely honest, I came extremely close to handing this one a four-star rating. It’s more a reflection of my recent reading mood than anything that had me rounding this strong three-point-five-star rating down.
Agent 21: Codebreaker follows the first two books in that it is an action-packed story, one which will have you turning the pages at a rapid pace. There is plenty to hold your attention, in regards to both the characters and the thriller aspects, yet there was something extra with this book to make it shine brighter than the two prior stories.
For me, this was the storyline. Following the ending of Agent 21: Reloaded, I expected to be thrown into more action regarding the underlying storyline that came about through the conclusion of events in book one. What we’re given is a story that takes a step away from what I expected. At first I was a wee bit unsure, fearful this was going to be a filler book, yet the storyline kept me hooked throughout. There was more to this one than the prior books, and it guaranteed I was more than willing to see how everything played out.
What stopped me from rounding up was how predictable some of the events where. As I’ve said with the prior books, however, this is a reflection of my views towards young adult thrillers rather than a reflection of the story itself. Had I been in a better reading mood, this one probably would have done enough to get that four-star rating from me.
Overall, Agent 21: Codebreaker is a strong addition to the Agent 21 series, one that will leave you curious as to where the story will go from here.
Agent 21: Codebreaker follows the first two books in that it is an action-packed story, one which will have you turning the pages at a rapid pace. There is plenty to hold your attention, in regards to both the characters and the thriller aspects, yet there was something extra with this book to make it shine brighter than the two prior stories.
For me, this was the storyline. Following the ending of Agent 21: Reloaded, I expected to be thrown into more action regarding the underlying storyline that came about through the conclusion of events in book one. What we’re given is a story that takes a step away from what I expected. At first I was a wee bit unsure, fearful this was going to be a filler book, yet the storyline kept me hooked throughout. There was more to this one than the prior books, and it guaranteed I was more than willing to see how everything played out.
What stopped me from rounding up was how predictable some of the events where. As I’ve said with the prior books, however, this is a reflection of my views towards young adult thrillers rather than a reflection of the story itself. Had I been in a better reading mood, this one probably would have done enough to get that four-star rating from me.
Overall, Agent 21: Codebreaker is a strong addition to the Agent 21 series, one that will leave you curious as to where the story will go from here.
December 28, 2017
By far my favourite of the series. The story line was well established and very- extremely suspenseful and interesting. Couldn’t put the book down at all!!! Highly recommended
April 4, 2022
I remember reading this series the first time, and this was my favourite book in the series.
But I read it this time and I was a little bored. The plot doesn't really happen for a while because the book is setting up Malcolm as an important future character, and then the plot kicks in and the characters just feel like they're running around doing spurious tasks for the sake of page filling. Its fast paced, but it felt like it was going nowhere for the longest time.
But I read it this time and I was a little bored. The plot doesn't really happen for a while because the book is setting up Malcolm as an important future character, and then the plot kicks in and the characters just feel like they're running around doing spurious tasks for the sake of page filling. Its fast paced, but it felt like it was going nowhere for the longest time.
September 18, 2022
3,5 ⭐️
Mit der Spannung eines guten Thrillers und unerwarteten Wendungen definitiv nicht nur für Jugendliche lesenswert.
Die zentralen Figuren sind allesamt charismatisch und spornen an die weiteren Teile zu lesen.
Mit der Spannung eines guten Thrillers und unerwarteten Wendungen definitiv nicht nur für Jugendliche lesenswert.
Die zentralen Figuren sind allesamt charismatisch und spornen an die weiteren Teile zu lesen.
July 27, 2014
Read the full review at: Polkadot's Book Blog
And then there was silence once more. Simply the rain on the cobblestones and the frenzied beating of his heart.
After reading this book, I can honestly say that this one is by my favourite in the series so far. It was so action-packed and completely nail-biting that I could not put it down, no matter how I tried, I kept coming back to it every 5 minutes to pick up where I left off. Which is why I finished it within a day!
By now you get all the things that you have come to expect from the series, suspense, mystery, thrilling adventures that lead you to an intense action-packed atmosphere. Yet this one feels that much more intense as the characters seem a little more developed and as a result older than the last two books, especially in terms of Zak. While Zak is only a year older than the previous book, he seems to have grown a lot more in his training.
In this book, the missions follows a series of bombings and terrorist threats so it was easy to see how this book was full of action. When one big thing ends another one starts so I was constantly thrown from one action, suspense filled scene to another. Never given enough time to recover before something else was happening, which I thought was just amazing!
All in all, there was not a lot I could find wrong with this book. It held up to it's expectations of the series, with it being completely gripping and unable to put down from the get go. It really excelled in it's genre because not only are you reading about espionage tricks you get the chance to learn them yourself. The characters were still strong and constantly developing, which makes it exciting to find out what they will be like in the fourth book. Once again encouraging you to continue with the series as they other books have always excelled in.
And then there was silence once more. Simply the rain on the cobblestones and the frenzied beating of his heart.
After reading this book, I can honestly say that this one is by my favourite in the series so far. It was so action-packed and completely nail-biting that I could not put it down, no matter how I tried, I kept coming back to it every 5 minutes to pick up where I left off. Which is why I finished it within a day!
By now you get all the things that you have come to expect from the series, suspense, mystery, thrilling adventures that lead you to an intense action-packed atmosphere. Yet this one feels that much more intense as the characters seem a little more developed and as a result older than the last two books, especially in terms of Zak. While Zak is only a year older than the previous book, he seems to have grown a lot more in his training.
In this book, the missions follows a series of bombings and terrorist threats so it was easy to see how this book was full of action. When one big thing ends another one starts so I was constantly thrown from one action, suspense filled scene to another. Never given enough time to recover before something else was happening, which I thought was just amazing!
All in all, there was not a lot I could find wrong with this book. It held up to it's expectations of the series, with it being completely gripping and unable to put down from the get go. It really excelled in it's genre because not only are you reading about espionage tricks you get the chance to learn them yourself. The characters were still strong and constantly developing, which makes it exciting to find out what they will be like in the fourth book. Once again encouraging you to continue with the series as they other books have always excelled in.
July 26, 2016
Chris Ryan has an addictive quality to his writing. It's so good, it catches me unawares. He has an impeccable style.
Zak's a good character. Sturdy, smart and reliable. He's not the kind to be tormented by the evil he sees. He knows how to move when he has to. His mental state is healthy.
Raf and Gabs always get into situations that just make me roll my eyes. You don't have to make smart characters stupid just so that main characters seems smarter. That's just lame.
I have to admit though, that I relished the arrogant and smug Michael getting into a bit of trouble. I can be sadistic like that.
Zak's a good character. Sturdy, smart and reliable. He's not the kind to be tormented by the evil he sees. He knows how to move when he has to. His mental state is healthy.
Raf and Gabs always get into situations that just make me roll my eyes. You don't have to make smart characters stupid just so that main characters seems smarter. That's just lame.
I have to admit though, that I relished the arrogant and smug Michael getting into a bit of trouble. I can be sadistic like that.
January 4, 2017
It took me few months to get back to this series, and it only took me some few hours to finish one book.
My God. How could I even describe this book? It's mildly intense read, if you are calm. But for me, who overthinks at some things, I nearly cried for some of the scenes. Okay, it was intense for me. Given that it was written so greatly, every chapter provides a good action-packed parts. Which makes a person think critically (on my part) for the conflicts and enjoy the book with those kind of scenes (on my part again).
I thorougly enjoyed reading the book. I'm up for the next. :)
PS. I really like Raf and Gabs together. They're cute.
PPS. I will try to learn those codes, too. Hehe.
My God. How could I even describe this book? It's mildly intense read, if you are calm. But for me, who overthinks at some things, I nearly cried for some of the scenes. Okay, it was intense for me. Given that it was written so greatly, every chapter provides a good action-packed parts. Which makes a person think critically (on my part) for the conflicts and enjoy the book with those kind of scenes (on my part again).
I thorougly enjoyed reading the book. I'm up for the next. :)
PS. I really like Raf and Gabs together. They're cute.
PPS. I will try to learn those codes, too. Hehe.
July 23, 2013
*coughs*
Okay...
4 - I love Zak. (HAHA)
5 - I can't wait for the next book(s).!
=))))))))))))
Okay...
4 - I love Zak. (HAHA)
5 - I can't wait for the next book(s).!
=))))))))))))
March 14, 2015
A terrorist bomber is threatening London. Zac to the rescue. Fast paced. Who will die? Who will survive? Very good read in this series.
September 25, 2018
Agent 21 Codebreaker by Chris Ryan is a very intense fiction book.
It made me think of it as fierce because of all the tragedy and mystery that happens throughout the book.
For example, in the book you think the bad guy is one person, but then the person suspected falls to the actual bad guy and then they are no closer to stopping the bad guy’s attacks. This made it very fiery because it messed with your mind.
In addition at one point the children's hospital is blown up and it is very extreme as they are trying to get the last of the sick children out of the building before the explosion happens. The book makes you feel like they need to save the kids, and there is always a sense of dread that they might not make it.
Therefore Agent 21 Codebreaker is a very intense book because of all of the tragedy and mystery that happens during the plot of the story. This book would be for people that love action and can stand gory detail.
It made me think of it as fierce because of all the tragedy and mystery that happens throughout the book.
For example, in the book you think the bad guy is one person, but then the person suspected falls to the actual bad guy and then they are no closer to stopping the bad guy’s attacks. This made it very fiery because it messed with your mind.
In addition at one point the children's hospital is blown up and it is very extreme as they are trying to get the last of the sick children out of the building before the explosion happens. The book makes you feel like they need to save the kids, and there is always a sense of dread that they might not make it.
Therefore Agent 21 Codebreaker is a very intense book because of all of the tragedy and mystery that happens during the plot of the story. This book would be for people that love action and can stand gory detail.
August 31, 2022
Read this once before but had forgotten most of it so it was almost like reading it for the first time!
I love this series a lot and these books are great to bridge the gap between the other books on my TBR list. They are aimed more at teenagers so for me they are quite an easy read which is nice when you want something more relaxed to read that doesn't get your brain working as hard to understand.
I love this series a lot and these books are great to bridge the gap between the other books on my TBR list. They are aimed more at teenagers so for me they are quite an easy read which is nice when you want something more relaxed to read that doesn't get your brain working as hard to understand.
October 3, 2025
“Codebreaker” shifts gears slightly by focusing more on the intellectual challenge of espionage—cracking codes, solving puzzles, and outthinking the enemy. It adds variety to the series and keeps it from being just another action-fest.
Still, some may feel it slows the pace compared to the previous books. Personally, I liked the mix of brains and brawn, which made Zak’s character development stand out.
Still, some may feel it slows the pace compared to the previous books. Personally, I liked the mix of brains and brawn, which made Zak’s character development stand out.
May 2, 2023
I can use the words exciting, gripping, suspenseful and enthralling in relation to this book, but only if I precede them all with NOT!!! I am not sure it would get a pass mark as a year 12 essay. To its credit though, it is a very quick read. To make it even quicker, read only the even pages - you won’t miss anything important!!
July 21, 2018
I think this book was a great addition to the Agent 21 series. Though I could see occasional times where I could predict the plot -- the voerall theme and concept of the book seems to be great! Suspense and thriller mixed with bait of irony.
Definitely a good read~
Definitely a good read~
September 6, 2018
I thought it was a very action packed book and I really enjoyed the gripping parts. I felt like it was hard to keep up with the storyline sometimes throughout the book. I couldn’t tell the genre either because it was changing a lot.
July 8, 2021
Spannend!!! London versinkt im Chaos,ein Bombenleger terrorisiert die englische Hauptstadt. Zak ist ihm auf der Spur, allein auf sich gestellt. Insgesamt ein rasantes Buch, welches schnell zu lesen ist.
April 5, 2023
The book was fun to read and gave the reader knowledge of a two step substitution cypher. Zac Darke AKA Harry Gold is at it again, this time in London, to save the day! Doing Crossword Puzzles, learning about the long-tailed shrike and in the process thwarts our criminal out for revenge.
May 17, 2025
Zac is tasked with stopping a bomber in central London. Good foreshadowing and genuinely unexpected turns. Three bombs and it is the job of Zac to stop them. The antagonist is not revealed until later and characters from the previous novels return.
This entire review has been hidden because of spoilers.
August 19, 2017
Didn't expect that Cruz would be involved. I was supprised, but good idea for bad guy to blow up the UK capital.
This entire review has been hidden because of spoilers.
January 2, 2018
The best Agent 21 book so far. Includes an even better plot twist than the last book, and loads of suspense.
August 9, 2018
This was, for me, the best book of the series so far... Zak, is learning to think before acting more... there was action, mystery, humour etc
May 11, 2020
WAAAAAY better than the first two books. I was considering not reading it but decided that i bought it so i might as well read it. Good job i did :)
June 13, 2021
AMAZING! I would highly recommend this book, to anyone who likes the previous 2, of the Agent 21 series, by Chris Ryan (ex SAS hero). I think I’m starting to get a new favourite author!!!!!
July 1, 2021
I loved this book so much. I was completely absorbed from the get go and was shocked when I reached the end. This is a wonderful book for people who enjoy the teen, mystery and spy category of books
March 24, 2024
4.5 stars
Read the book in one sitting, stayed up until 4am reading it!
Action packed and entertaining as has come to be expected with this series.
Read the book in one sitting, stayed up until 4am reading it!
Action packed and entertaining as has come to be expected with this series.
May 16, 2025
Surprisingly I quite enjoyed it!
August 15, 2019
Sooooo excited for the rest of the series!
July 8, 2015
Codebreaker was better then previous two novels in the Zak Darke series and I enjoyed it, but even though I gave it a 4 it's more of a 3.5 simply because there were things that really didn't sit right with me.
Cruz Martinez again. He's like the greatest villain ever it seems which is kind of silly. He's involved with everything when he was supposed to be a kid of a drug dealer.
Second, Zak gets placed into Daily Post and by accident he gets assigned to the man who turns out to be the BAD GUY. I mean come on! :D At least he could have stumbled into Rodney/Lee while at Post spying on Ludgrove and got some info about him that way. Some things would have had to be written bit differently but it would have been far more believable and honestly a better story.
Same with the codebreaking, he learns about codebreaking a day before he needs it... Could have been a flashback at least, as in "Zak recalls couple of months ago when Raf and Gabs taught him codebreaking..." or something better written.
I understand this is a YA novel and I might be too critical but things like that usually get under my skin :)
Anyway all in all I enjoyed reading this.
Also for someone who claims to not read YA novels a lot, lately I've found I've read quite a few (even checked my read section, quite a few there this year :P). Zak Darke is a decent series but I still prefer the Body(Buddy)guard series, somewhat similar as they are.
Cruz Martinez again. He's like the greatest villain ever it seems which is kind of silly. He's involved with everything when he was supposed to be a kid of a drug dealer.
Second, Zak gets placed into Daily Post and by accident he gets assigned to the man who turns out to be the BAD GUY. I mean come on! :D At least he could have stumbled into Rodney/Lee while at Post spying on Ludgrove and got some info about him that way. Some things would have had to be written bit differently but it would have been far more believable and honestly a better story.
Same with the codebreaking, he learns about codebreaking a day before he needs it... Could have been a flashback at least, as in "Zak recalls couple of months ago when Raf and Gabs taught him codebreaking..." or something better written.
I understand this is a YA novel and I might be too critical but things like that usually get under my skin :)
Anyway all in all I enjoyed reading this.
Also for someone who claims to not read YA novels a lot, lately I've found I've read quite a few (even checked my read section, quite a few there this year :P). Zak Darke is a decent series but I still prefer the Body(Buddy)guard series, somewhat similar as they are.
This entire review has been hidden because of spoilers.
May 27, 2017
Gosh this book. People will say it's similar to CHERUB or Henderson Boys, but I have to admit that Chris Ryan has his own style of writing that really reflects that he was out there in the field.
There were constant twists and turns in the book when I felt it was all over but it turned it wasn't. I would recommend this to anybody who loves a good action book with a long and well-thought out plot that carries on through each book.
There were constant twists and turns in the book when I felt it was all over but it turned it wasn't. I would recommend this to anybody who loves a good action book with a long and well-thought out plot that carries on through each book.
June 17, 2013
The young secret agent, Zac Darke, is back for his third mission. As always the stakes are high. An unknown bomber has begun a terror campaign in London and when an explosion on the tube leaves commuters dead and injured, Zac and his team are brought in. They are expected to work out how this terror cell operates and anticipate any future targets. The clues are scarce and they have no idea where, or when, the bomber will strike next. An unexpected source might be the break they need. A teenage hacker, Malcolm, currently detained in a young offender's institute, claims he has the answer but he doesn’t trust anyone, especially adults. Zac is sent in to question him but before they get a chance to talk he is shot by others who have a vested interest in Malcolm's capabilities. Malcolm falls into a coma and Zak must puzzle out what clues he had pieced together. There is a short timeline so Zac needs to work fast if he is to break the cipher before another bomb goes off. Who is the bomber and what is behind his reign of terror? Zak and his team are up against a ruthless and cunning foe.
Displaying 1 - 30 of 45 reviews