Agent 21
Goodreads ratings
4.1 / 5

"Agent 21" Summary

By Chris Ryan

young adult | 355 pages | Published in NaN

When Zak Darke's parents die in an unexplained mass murder he's left alone in the world. That is until he's sought out by a mysterious man: ‘I work for a government agency,’ the man tells him. ‘You don’t need to know which one. Not yet. All you need to know is that we’ve had our eye on you. There’s a possibility you could help us in certain . . . operational situations.’Zak becomes Agent 21. What happened to the 20 agents before him he'll never know. What he does know is that his life is about to change for ever . . .


Estimated read time: 6 min read

One Sentence Summary

A young boy is recruited into a secret intelligence agency and trained to become an elite undercover agent.


"Agent 21" by Chris Ryan is a thrilling young adult novel that delves into the world of espionage and covert operations. The story follows the journey of Zak Darke, a fifteen-year-old who finds himself thrust into the dangerous world of the secret service. Filled with action, intrigue, and moral dilemmas, "Agent 21" takes readers on a gripping adventure as Zak navigates the complexities of espionage and the challenges of adolescence.

Brief Synopsis

Plot Overview

The story is set in modern-day England and various international locations. Zak Darke, a talented and athletic fifteen-year-old, is suddenly orphaned when his parents die in a car accident. Shortly after the funeral, Zak is approached by a mysterious man named Mr. Smith, who reveals that Zak's parents were actually undercover agents for a secret government organization known as the "Agents." Mr. Smith offers Zak the chance to follow in his parents' footsteps and become an Agent himself.

Reluctantly, Zak agrees and is put through a grueling training program that puts his physical and mental abilities to the test. As he learns the skills necessary to become a covert operative, Zak also uncovers shocking truths about his parents' past and the dangerous world of espionage. When a mission goes awry, Zak finds himself in a race against time to stop a deadly terrorist plot and prevent a global catastrophe.


The novel primarily takes place in contemporary England, with some scenes set in other European countries and the Middle East. The story unfolds in both urban and rural settings, from the bustling streets of London to the remote countryside. The contrast between Zak's ordinary teenage life and the high-stakes world of espionage creates a dynamic backdrop for the narrative.

Main Characters

The story features several key characters who play pivotal roles in Zak's journey:

Zak DarkeThe fifteen-year-old protagonist who becomes embroiled in the world of espionage after the death of his parents. He is resourceful, determined, and skilled in physical combat.
Mr. SmithA mysterious operative who recruits Zak into the world of the Agents. He serves as Zak's mentor and guide, providing him with training and guidance as he prepares for dangerous missions.
EthanZak's best friend and confidant, who becomes entangled in the web of secrets and peril that Zak faces. Ethan provides emotional support and plays a crucial role in Zak's journey.
SarahA fellow Agent who becomes Zak's partner on a critical mission. She is skilled, intelligent, and determined, serving as a mentor figure for Zak as he navigates the complexities of espionage.

Story Points Over Chapters

Chapters 1-5

Zak's ordinary life is shattered by the sudden death of his parents in a car accident. He is approached by Mr. Smith, who reveals the truth about his parents' identity as Agents and offers Zak the opportunity to join the organization. Zak begins his intense training, learning combat skills, surveillance techniques, and the art of deception.

Chapters 6-10

Zak's training intensifies as he hones his abilities in marksmanship, hand-to-hand combat, and evasion tactics. He grapples with the emotional weight of his parents' secret lives and the moral implications of becoming an Agent. Meanwhile, he forms a close bond with his friend Ethan, who becomes increasingly curious about Zak's newfound skills.

Chapters 11-15

Zak is assigned his first mission alongside the experienced Agent Sarah. As they delve into the heart of a complex terrorist plot, Zak confronts the harsh realities of espionage and the sacrifices required to protect innocent lives. The mission tests his courage, resourcefulness, and loyalty as he faces life-threatening challenges.

Chapters 16-20

The mission takes a perilous turn, forcing Zak to make split-second decisions that will determine the outcome of the operation. As the stakes escalate, Zak relies on his training and instincts to outmaneuver the adversaries and prevent a catastrophic attack. The tension builds to a heart-pounding climax as Zak confronts the ultimate test of his abilities and resolve.

Main Events

  1. Zak's recruitment into the world of the Agents after the death of his parents.
  2. Intensive training and preparation as Zak learns the skills necessary to become a covert operative.
  3. Zak's first mission alongside Agent Sarah, uncovering a complex terrorist plot with global implications.
  4. High-stakes confrontations and life-threatening challenges as Zak races against time to thwart the deadly threat.
  5. Zak's moral and emotional journey as he grapples with the realities of espionage and the sacrifices it demands.

Themes and Insights


  1. Identity and Belonging: Zak struggles with the revelation of his parents' secret lives and the implications for his own identity and sense of belonging.
  2. Moral Complexity: The novel explores the ethical dilemmas faced by covert operatives, as Zak grapples with the choices he must make in the line of duty.
  3. Courage and Resilience: Zak's journey highlights the importance of courage, resilience, and adaptability in the face of adversity and danger.
  4. Betrayal and Trust: The story delves into themes of betrayal and trust, as Zak navigates a world where loyalties are constantly tested.


The novel provides insights into the demanding and often morally ambiguous world of espionage, shedding light on the psychological and emotional toll it takes on those involved. It also offers a nuanced portrayal of teenage resilience and the capacity for young individuals to rise to extraordinary challenges when faced with extraordinary circumstances.

Reader's Takeaway

"Agent 21" offers readers a gripping and immersive exploration of the world of espionage through the eyes of a young protagonist. The novel is packed with action, suspense, and thought-provoking moral dilemmas, making it a compelling read for fans of spy thrillers and adventure stories. Readers will find themselves captivated by Zak's journey as he navigates the treacherous terrain of secret missions and personal growth.


"Agent 21" by Chris Ryan delivers a captivating blend of action, intrigue, and moral complexity, offering readers a thrilling glimpse into the world of covert operations. With a relatable teenage protagonist, high-stakes missions, and thought-provoking themes, the novel is sure to leave a lasting impression on readers of all ages. As Zak Darke's story unfolds, readers are taken on a gripping journey that explores the complexities of identity, morality, and the indomitable spirit of resilience in the face of danger.

Agent 21 FAQ

  1. What is 'Agent 21' about?

    Agent 21 is a young adult novel about a 14-year-old boy named Zak Darke who is recruited by a government agency to become a teenage spy. He undergoes intense training and is sent on a dangerous mission to stop a terrorist plot.

  2. Who is the author of 'Agent 21'?

    The author of 'Agent 21' is Chris Ryan, a former British Special Forces operative and the bestselling author of several military thriller novels.

  3. Is 'Agent 21' suitable for all ages?

    While 'Agent 21' is classified as a young adult novel, it contains themes of espionage, danger, and violence, so it may not be suitable for very young readers. It is best for older children and teenagers.

  4. Are there sequels to 'Agent 21'?

    Yes, there are sequels to 'Agent 21' including 'Agent 21: Reloaded' and 'Agent 21: Codebreaker', which continue the story of Zak Darke and his adventures as a teenage spy.

  5. Is 'Agent 21' part of a series?

    Yes, 'Agent 21' is the first book in a series of young adult spy thrillers written by Chris Ryan. The subsequent books follow the further exploits of Zak Darke.