Sixteen-year-old Miles is a biracial teenager from Brooklyn attending the elite Brooklyn Visions Academy. Secretly operating as the superhero Spiderman, he constantly balances his family expectations, his community roots, and his hidden responsibilities. While he generally prefers to avoid conflict, his strong moral compass compels him to protest his history teacher's racist rhetoric, resulting in a day-long in-school suspension.

Alicia is a bold and politically active student at Brooklyn Visions Academy. She shares Miles's passion for spontaneous activism and refuses to tolerate bigotry in the classroom. Sent to in-school suspension for leading an anti-discrimination chant, she spends the day exchanging thoughtful poetry with Miles and supporting his community initiatives.

Tobin is a quiet boy who works in the school library. His presence in suspension surprises his peers, who typically know him as introverted and rule-abiding. Throughout the day, he exhibits increasingly strange and unsettling behavior, such as eating paper and interacting strangely with insects, which triggers Miles's heightened intuition.

Ganke is Miles's roommate and best friend at Brooklyn Visions Academy. As one of the few people who knows Miles's secret identity, he provides essential emotional support and a safe space for Miles to be himself. He tries to pass messages to Miles during the suspension and offers comedic relief during tense moments.

Mr. Chamberlain is a history teacher at Brooklyn Visions Academy who uses his position of authority to promote historical inaccuracies and racist views. When he claims that enslaved people enjoyed their circumstances, he provokes a classroom rebellion. He specifically targets Miles for humiliation, initiating the central conflict of the school day.

The Warden is a 400-year-old villain who infects people with racist attitudes and pushes vulnerable youths into lives of crime. Though Miles recently defeated him, the villain's dark influence still lingers over the school and Miles's family history.

Aaron is Miles's deceased uncle who lived a life entrenched in crime. Though he made poor choices that eventually led to his death, Miles remembers him affectionately and struggles to reconcile the man's criminal legacy with his familial bond. His history heavily influences Miles's fears about his own path in life.

Austin is Miles's cousin and Uncle Aaron's son. Currently serving time in prison, he acts as a living reminder of the family's troubled legacy. Miles worries deeply about Austin's future and plans to organize a book drive to support incarcerated youths like him.

Miles's father is a strong moral presence in his son's life. Having actively chosen to break away from the criminal lifestyle that claimed his brother Aaron, he provides Miles with grounded advice on how to fight darkness with light and handle institutional pressure.

Miles's mother is a caring parent who supports her son's right to stand up for himself, though she also advises him to survive the school's strict expectations. Miles actively conceals the dangerous aspects of his life to spare her from anxiety.

Brad is a classmate at Brooklyn Visions Academy who joins Miles and Alicia in chanting against Mr. Chamberlain's racist history lesson. As a result, he is placed in in-school suspension for the day.

Coach Holt is the staff member assigned to monitor the in-school suspension room. He ensures the students complete the worksheets provided by their regular teachers and maintains order throughout the long day.

Mrs. Tripley is the librarian at Brooklyn Visions Academy. She manages the school's book collection and deals with an unusual termite problem affecting the library's resources. Miles saves her from a falling tree during a fire drill.