Jabari, known as J.B., is a quiet and observant Black junior living in the Benning Terrace housing projects. After he struggled in public schools, his mother enrolled him at Promise Prep to secure a better education. He battles severe anxiety, often sweating uncontrollably when nervous, and resents the school's restrictive policies despite acknowledging the academic benefits.

Trey is a popular student and star basketball player at Promise Prep. He frequently gets into trouble for making jokes during class and is widely viewed as the class clown. Raised by his uncle after his father's death, Trey faces intense pressure and physical discipline at home, mirroring the strict control he experiences at school.

Ramón is a Salvadoran student who migrated to the United States with his family. He has a passion for culinary arts and dreams of opening his own restaurant. He wakes up early each morning to cook food with his grandmother, selling the meals at school to save money for his future business. He constantly fights against peers' negative assumptions regarding his family's gang ties.

Kenneth Moore is the founder and principal of Urban Promise Prep. He developed the strict "Moore Method," a zero-tolerance educational system designed to heavily discipline and control minority students. His sudden murder in his office serves as the inciting incident for the investigation. Prior to his death, rumors circulate regarding his erratic mood swings and severe financial issues.

Terrance, commonly known as Uncle T, is a former Marine and Trey's legal guardian. He took custody of Trey after his sister struggled with substance use and Trey's father passed away. He enforces rigid rules at home and uses physical violence as a form of discipline, believing it is the only effective way to raise a young man.

Wilson Hicks is the Dean of Students and co-founder of Promise Prep. He enthusiastically enforces the school's militaristic policies, using an electronic tablet to issue demerits for minor uniform or behavioral infractions. He frequently disciplines students for failing to walk exactly on the blue line painted in the hallways.

Omar is a quiet student who assists in the school office. He strongly prefers to remain anonymous and invisible, acting as an observer rather than a participant in school events. He spends his time documenting the school environment through photography and film projects.

Stanley Ennis is a wealthy entrepreneur and the largest financial donor to Urban Promise Prep. He views the school's strict disciplinary model as a highly successful system that could be franchised nationally for prestige and profit.

Mrs. Hall is a teacher who has worked at Promise Prep since its opening. Unlike the administration, she strongly opposes the school's prison-like environment and advocates for treating the students with compassion and respect. She claims to be on maternity leave around the time of the murder but is seen around the school.

Keyana is a student at Anacostia High School and J.B.'s romantic interest. She is deeply supportive and loyal, immediately believing in J.B.'s innocence. She actively assists him in investigating the school community and organizing lists of potential suspects.

César is Ramón's older cousin and a prominent leader of the Dioses de Humo gang. Jaded by societal barriers, he believes traditional paths to success are impossible for people of color. He consistently pressures Ramón to abandon school and join his criminal enterprise.

Doña Gloria is Ramón's grandmother, referred to affectionately as his abuela. She cooks traditional Salvadoran recipes with Ramón every morning and remains a steadfast source of unconditional love. She performs spiritual cleansings to protect him from the chaotic events surrounding the murder.

Magdalena is Ramón's cousin and César's younger sister. She serves as a crucial confidante for Ramón during the investigation and worries deeply about her brother's dangerous lifestyle choices.

Ms. Williamson is J.B.'s mother. She works extra shifts to provide for her son and enrolled him at Promise Prep with the hope of securing him a safer, more structured educational future. She tries to protect him by grounding him after his arrest.

Luis is a student at Promise Prep and a close friend of Ramón. He actively helps Ramón sell food at school and assists the group in gathering information during their independent investigation.

Brandon is Trey's best friend and a star player on the Promise Prep basketball team. He notices Trey acting strangely on the morning of the murder but struggles to balance his loyalty to Trey with his mother's demands to stay away from the investigation.

Coach Robinson leads the basketball team at Promise Prep. He played college basketball with Moore and credits the principal for providing him a second chance at a career. He strongly believes in Trey's good character.

Solomon is a Promise Prep student with an Ethiopian accent. He frequently gets teased by Trey but pays close attention to the school's internal dynamics and office schedules, providing useful information to the investigation.

Nico is a cafeteria worker at the school and a former member of the Dioses gang. His past affiliations and secret meetings make him a prominent person of interest during the students' investigation.

Ever is a member of the Dioses gang. He approaches Ramón at the bus stop and attempts to leverage Ramón's anger toward Principal Moore to recruit him into carrying out revenge.

Mr. Reggie is the School Resource Officer at Promise Prep. He supervises the detention room on the day of the murder and is one of the first adults to respond to the sound of the gunshot.

Nurse Robin is the medical employee at Urban Promise Prep. She openly dislikes the toxic masculinity fostered by the administration and worries constantly about Moore's erratic behavior and possible alcohol use.

Detective Bo is one of the harsh police investigators assigned to Principal Moore's murder. He uses aggressive interrogation tactics, yells at the suspects, and immediately assumes the three boys are guilty based on their backgrounds.

Trey's mother lives in New York City and lost custody of Trey years ago due to substance use issues. She travels to Washington, DC, to support her son after he is questioned by the police, offering him a rare moment of maternal understanding.

Bando is a neighborhood hustler in J.B.'s community. He occasionally sells marijuana to the local youth and attempts to sell J.B. a weapon shortly before the murder occurs.

Unk is an older neighborhood man who closely observes the local community. While he initially claims not to care about the prep school, he later steps out of the shadows to offer the boys crucial advice about looking at the bigger picture.

Rachel is the older sister of a Promise student. She is highly suspicious of Ramón due to his family's known gang affiliations and reports her concerns directly to the school administration.

Tony is a student at Promise Prep. Unlike his sister, he respects Ramón's culinary skills and the initiative he brings to the school cafeteria, though he harbors quiet doubts about how Ramón makes his money.