Jessamy is an eight-year-old girl who lives with her English father and Nigerian mother. She is highly intelligent, observant, and introverted, preferring to read books and write haikus rather than play outside. During a trip to her grandfather's compound in Nigeria, she experiences a severe culture clash and struggles to feel comfortable.

TillyTilly is a barefoot Nigerian girl around Jessamy's age who roams the family compound unseen by adults. She possesses unusual physical abilities, such as unlocking heavy gates and bypassing security at an abandoned amusement park. She encourages Jessamy to break rules and keep their interactions completely hidden from adults.

Sarah is a Nigerian-born woman who moved to England fifteen years ago to study medicine before switching to English literature and becoming a writer. She attempts to bridge the cultural gap between her traditional Nigerian upbringing and her daughter's English environment, often using harsh discipline that causes friction with her husband.

Daniel is an English man who defends his daughter's introverted behavior against his wife's concerns. He attempts to learn Yoruba and participate in Nigerian customs during their family trip but finds it difficult to adapt to the extended family's dynamics and his father-in-law's expectations.

Baba Gbenga is the patriarch of the Oyegbebi family, living in a three-story main house built by his grandfather in the 1870s. He is a devout Baptist who openly disapproves of his daughter's literature career and English marriage, yet he shows immediate affection for his granddaughter.

Siobhan is the talkative daughter of Jessamy's psychologist. She openly breaks her mother's rules by hiding sweets in her bedroom. She initiates a friendship with Jessamy, impressed by her ability to read Shakespeare, and offers her a rare chance at normal socialization.

Dr. McKenzie is a psychologist who evaluates Jessamy after she experiences behavioral struggles and tantrums at school. He treats his sessions with her more like casual conversations, earning her trust and encouraging her to articulate her fears about feeling different.

Colleen is a popular student in Jessamy's Year Four class who frequently targets her with insults. Her confident school persona masks a difficult home life involving aggressive parenting and personal struggles that she desperately tries to hide.

Dulcie is Jessamy's cousin on her father's side. She constantly seeks adult approval and finds her cousin's withdrawn behavior strange, leading to tension when they are forced to spend a weekend together under the supervision of a babysitter.

Aunty Funke is one of Sarah's relatives living on the family compound in Nigeria. She manages daily household tasks, watches over the younger children, and takes Jessamy and her cousins on an outing to the local zoo.

Mr. Heinz is the headmaster at Jessamy's school in England. He recognizes her academic intelligence, even offering to move her up a year, but he struggles to handle her emotional outbursts and social isolation.

Miss Patel is Jessamy's teacher in England. She attempts to manage Jessamy's unpredictable classroom behavior but often finds herself physically struggling to contain the young girl during intense panic attacks.