Alex is a 14-year-old student living in West London who is abruptly thrust into the world of espionage following the sudden death of his uncle, Ian. Athletic, perceptive, and highly trained in martial arts and outdoor survival, Alex possesses a natural aptitude for spy work. Despite his skills, he longs for a normal teenage life and resents being forced into a dangerous undercover mission by British intelligence.

Alan Blunt is the chief of MI6's Special Operations division and Alex's new employer. Pragmatic, expressionless, and coldly objective, he prioritizes the defense of Britain above all else, including the safety of his agents. He recognizes Alex's extraordinary potential and ruthlessly leverages the boy's circumstances to recruit him for a high-risk mission.

Mrs. Jones is Alan Blunt's secretary and second-in-command at Special Operations. She frequently issues instructions to spies and government officials, operating with the same dedication to national security as her boss. However, she displays more sensitivity and concern regarding the immense dangers placed on their young recruit.

Herod Sayle is an Egyptian multi-millionaire and the founder of the technology company Sayle Enterprises. Adopted by a wealthy British couple as a child, he projects a generous, charismatic public image by promising to donate advanced Stormbreaker computers to English schools. Beneath his charming facade, he harbors deep-seated bitterness from enduring severe racism and xenophobia during his childhood.

Yassen Gregorovich is a highly skilled, remorseless Russian contract killer connected to the secretive operations at Sayle Enterprises. He is coldly efficient, viewing his lethal profession purely as a business transaction. Intolerant of failure or incompetence, he strikes fear into his peers while operating with chilling precision.

Ian Rider is Alex's late uncle and guardian, supposedly a quiet bank manager whose frequent travels required him to be away from home. In reality, he was a highly trained MI6 spy who secretly prepared his nephew for the world of espionage by teaching him martial arts, extreme sports, and survival skills.

Jack Starbright is an American student who originally came to England to study and took a job as Ian Rider's housekeeper. Over time, she has become Alex's closest friend and defacto guardian, offering him emotional support and a sense of stability in an otherwise chaotic world.

Smithers is a brilliant technician working for MI6 who designs specialized gadgets for field agents. Because Alex is too young to carry a firearm, Smithers crafts ingenious tools disguised as ordinary teenage items, such as an acne cream and a modified Game Boy, to assist the boy on his mission.

Mr. Grin is Herod Sayle's mute butler and loyal enforcer. A former circus performer who used to catch knives with his teeth, he suffered a horrific accident that mutilated his mouth and severed his tongue. He now serves as a silent, imposing presence in Sayle's household.

Nadia Vole is a strict German woman who works closely with Herod Sayle. She supervises operations at Sayle Enterprises and manages Alex's schedule, maintaining a watchful eye on the young undercover agent while keeping the restricted areas of the facility secure.

Wolf is an adult military trainee who openly mocks Alex during MI6's rigorous training program, dubbing him "Double 0 Nothing." He resents the presence of a teenager in an elite adult unit, but their dynamic shifts as the grueling exercises test both of their limits.

Crawley operates under the guise of a manager at the Royal & General bank. He acts as an intermediary for Alan Blunt, maintaining the MI6 front operation and facilitating the agency's aggressive recruitment of their newest operative.