Brooklyn is a 12-year-old hacker born in Puerto Rico who has spent years moving through the foster care system. She relies on her computer skills to protect vulnerable children and expose abusive situations, which initially lands her in family court. Upon meeting Mother, she embraces the opportunity to join a covert spy team operating out of a Scottish airfield. She operates at a high level of technical proficiency but struggles with a severe fear of heights and a tendency to hide her emotional vulnerability.

Mother is an eccentric MI6 secret agent who leads a clandestine group of young spies. He operates out of a stone house in Scotland and uses various aliases to conduct international operations without drawing attention. He bears burn scars on his arm from a past mission in a French factory. While guiding the young operatives, he continuously searches the globe for his missing biological family.

Sydney is an Australian physical trainer for the spy group who maintains a strong sense of right and wrong. Mother discovered her after she destroyed a statue of a racist headmistress at her boarding school. She brings optimism and humor to the team, quickly befriending Brooklyn and helping her adjust to the group's dynamics. She runs exceptionally fast and remains unapologetic about fighting systemic inequality.

Paris is a Rwandan refugee who serves as the navigator and unofficial older brother of the spy team. He was the first child Mother adopted after they met during a sting operation in an abandoned French factory. He provides stability and a calm presence for the younger team members. He possesses deep knowledge of the Parisian catacombs and remains highly observant of his surroundings.

Kat is a codebreaker and pattern decoder originally from Nepal. She possesses savant-like abilities in mathematics and cryptography but requires specific routines to feel comfortable. She is highly particular about seating arrangements and initially keeps her distance from new arrivals. She sees the world in equations, allowing her to find hidden patterns in complex corporate data.

Rio is the team's deception master, found by Mother while performing magic tricks on the streets of Rio de Janeiro. As the youngest member of the group, he often struggles with his confidence and desperately wants to be taken seriously by his peers. He utilizes sleight of hand and misdirection to assist the team in restricted areas.

Le Fantôme is the criminal mastermind and leader of the international crime syndicate Umbra. He orchestrates attacks and thefts globally, operating from the shadows to acquire valuable art and dangerous technology. He oversees the deployment of field agents to disrupt international security agencies.

Dr. Alexandra Montgomery, known as Monty, is a cryptographer and weather analyst who helps Mother supervise the young operatives. She manages the supercomputer Ben and maintains a steady, encouraging presence at the Scottish base. She shares Brooklyn's passion for computer science and often asks the children philosophical questions about technology and art.

Charlotte is a former member of Mother's spy team who was dismissed for using her hacking abilities for personal greed. She now leads a rival team from Kinloch Abbey in the environmental youth summit. She dresses sharply and views hacking as a competitive sport, setting up an immediate and tense rivalry with Brooklyn.

Stavros Sinclair is a wealthy tech giant and environmental activist who owns the massive corporation Sinclair Scientifica. He hosts a high-stakes competition to encourage youth to develop climate change solutions, drawing the attention of MI6. He speaks in a highly scripted manner and collects rare Impressionist art in a private museum.

The Professor is a highly educated chemist and assassin who executes dark deeds for Umbra. He handles dangerous materials, including a newly developed virus stolen from a French research laboratory. He operates as a ruthless field operative capable of moving unnoticed through high-security events.

Gertrude Shepherd is a senior MI6 agent and Mother's direct supervisor. She coordinates the team's involvement in Operation Willy Wonka and sets their specific objectives regarding Sinclair's servers. She expects high performance and closely monitors the physical capabilities of the young operatives.

Reggie is a long-time MI6 agent who manages a secure inn for British intelligence. He oversees a facility equipped with bulletproof windows, signal disrupters, and hidden exits. He maintains a one-star rating for the establishment to actively deter civilian guests.

Mother's Wife is a highly skilled operative who vanished under mysterious circumstances years prior. Her disappearance, along with their children, drives Mother's relentless global search. She operates from the shadows and communicates strictly through hidden channels.

The missing biological children of Mother who disappeared along with his wife. Their absence leaves a massive void in Mother's life, prompting him to adopt other orphaned children while secretly tracking their whereabouts.

Abusive guardians who took in Brooklyn and other children solely to collect state funds. They punished the children severely, locking them in closets and outside. Their financial crimes trigger Brooklyn's hacking attempts.

The deceased grandmother of Brooklyn. She passed away when Brooklyn was seven years old, leaving the young girl to enter the foster care system. She gifted Brooklyn a snow globe that becomes a symbol of family connection.

Ben is a wall-to-wall supercomputer used by the team for weather studies and advanced cryptography. Named after a famous Spanish priest and meteorologist, it serves as the technological backbone of the spy group. It is housed in a historical hiding space beneath the Scottish base.