Leo is a 12-year-old boy raised by his widowed mother. He possesses a highly active imagination and views the world through the lens of the zodiac, believing the upcoming twentieth century will bring a magical golden age. Arriving at Brandham Hall, he feels deeply self-conscious about his heavy winter clothing and lower social status. He relies on magical thinking to make sense of the intimidating adult world around him.

Marian is the beautiful daughter of the wealthy Maudsley family. She intervenes when Leo feels humiliated by his winter clothes, taking him to Norwich to purchase a lighter green suit. She projects charm and vitality, making her a central figure at the estate. She carefully manages her social obligations while maintaining private correspondences out of sight of her family.

Ted is a tenant farmer who leases Black Farm on the local aristocratic estate. He spends his days engaged in physical agricultural labor and possesses an unrefined, natural masculinity. He interacts with the estate guests during village activities like the annual cricket match. He eventually enlists Leo to carry unsigned notes on his behalf.

Hugh is an aristocratic gentleman who carries a significant facial scar from his military service in the Boer War. He represents the established social order of Edwardian high society. He treats the younger guests with gentle courtesy, playfully assigning Leo the nickname of a Roman messenger god. His ancestral title casts a long shadow over the local community.

Mrs. Maudsley is the matriarch of the family leasing Brandham Hall. She maintains a watchful, commanding presence over the household. She focuses intensely on social propriety and closely monitors the interactions of her children and guests. Her fixed, dark gaze makes Leo feel deeply scrutinized and uncomfortable.

Marcus is Leo’s schoolmate who invites him to spend July in Norfolk. He acts as an enforcer of upper-class behavioral codes, instructing his friend on proper etiquette and dress. He enjoys gossip and closely observes the romantic developments within his family, occasionally attempting to gain his mother's favor by sharing what he knows.

Mr. Maudsley is a quiet city financier who has leased the imposing Georgian estate for his family. He possesses a drooping mustache and often keeps to himself, occasionally asking polite but brief questions of his guests. He demonstrates careful, shrewd calculation during the village cricket match, preferring tactical placement over raw power.

Denys is Marcus and Marian's older brother. He participates in the estate's leisure activities, including bathing parties and the annual cricket match. He occasionally clashes with his mother over household decisions, particularly regarding how much freedom the younger guests should be allowed.

Mrs. Colston is Leo's widowed mother. She lives frugally near Salisbury following the death of her husband, a former bank manager. She corresponds with her son during his trip and refuses his sudden request to return home early, misunderstanding the true nature of his distress.

Jenkins is an older boy at Leo's preparatory school, Southdown Hill. He targets Leo for using elevated language, subjecting the younger boy to physical bullying before suffering a severe accident.

Strode is a student at Southdown Hill who participates in tormenting Leo. He falls from the school roof alongside his friend, an event that elevates Leo's reputation among the other students who believe a curse caused the accident.

Nannie Robson is the elderly former caretaker for the Maudsley family. She lives in a cottage near the estate. Her poor memory makes her a convenient excuse for younger family members seeking to explain their absences from the main house.