Benjamin is an ordinary twelve-year-old boy with a talent for complex mathematics who is suddenly recruited to the CIA's Academy of Espionage. He struggles to fit in among highly trained, physically adept peers. Instead of relying on combat skills, he uses his intellect and situational awareness to survive the sudden, dangerous challenges of his new environment.

Erica is a fifteen-year-old student at the spy academy known for her cold demeanor and exceptional espionage skills. Coming from a legacy family of spies, she possesses deep knowledge of the campus and high-level physical combat abilities. She views Benjamin's lack of training with disdain but finds herself working closely with him.

Alexander is a well-known CIA agent who presents himself as a suave, highly accomplished operative. He brings Benjamin to the Academy of Espionage, promising an exciting life of saving the world. He maintains an image of constant readiness and boasts of high-profile, dangerous missions.

Murray is a repeat student at the spy academy who deliberately aims for a low-risk desk job rather than field work. He serves as an early guide for Benjamin, explaining the harsh realities and social dynamics of the school. He actively avoids physical exertion and prefers to observe the chaos from a safe distance.

Chip is a polished, handsome, and intimidating older student at the academy. He frequently attempts to coerce other students into doing his work for him. He targets Benjamin early on, assuming the new student's cryptography scores make him an easy mark for cheating schemes.

Zoe is a fellow student who develops an immediate fascination with Benjamin. She convinces herself and others that Benjamin is a highly capable undercover operative using a fake persona to hide his true lethal skills. She is friendly and fiercely defends Benjamin against his detractors.

Warren is a student at the spy academy who frequently spends time with Zoe. He has a strong interest in physical stealth and often practices blending into his environment. He utilizes elements like tree sap, moss, and dirt to create elaborate, literal camouflage suits.

Greg is a large, physically powerful student who acts as muscle for Chip Schacter. He uses his imposing size to intimidate others, demonstrating his strength by easily crushing a metal dining hall spoon in one hand to threaten Benjamin.

Mike is Benjamin's best friend from his normal life before the CIA. He remains unaware of the spy academy's true nature, believing his friend attends a boring magnet school. He provides a tether to Benjamin's old life, frequently messaging him about regular middle school events.

Tina is a resident advisor at the Armistead Dormitory. She is responsible for the students living on her floor and is quick to respond to potential threats. Her readiness to draw a weapon reflects the constant state of high alert maintained by the academy's staff and older students.

Professor Crandall is a seemingly boring instructor at the academy. He maintains a strict classroom environment and is known to violently test students who do not pay attention. He suddenly deploys ninjas to attack disruptive pupils to prove a point about constant vigilance.

Barnabus Sidebottom is the principal of the CIA's Academy of Espionage. He is highly critical of his students and dismissive of Benjamin's abilities. He frequently threatens severe punishments, such as locking students in a secure underground cell called the Box.

Elizabeth is a girl from Benjamin's normal middle school. She represents the regular, non-espionage life he left behind when he joined the academy. Mike frequently updates Benjamin on her social activities to tempt him back home.

Kirsten is a student at the academy who associates with Chip Schacter's group. She follows Chip's lead in intimidating new students and helps reinforce his authority over the younger peers.