Callum is an 11-year-old boy living with his family on a rural sheep farm in coastal Scotland. He possesses a kind, sensitive nature, which often puts him at odds with the aggressive peer pressure exerted by his school friends. His deep fascination with wildlife drives him to spend hours outdoors, eventually leading to his discovery of a rare bird nesting on his family's property.

Iona is an 11-year-old girl who recently returned to the coastal Scottish village from London to live with her grandfather. She is deeply attuned to nature, spending her time wandering outdoors barefoot and discovering secrets about the local wildlife. Her family's past has made her a target for bullying and ostracization from the other children at school, leading her to seek solace in the wilderness.

Iris is a wild female osprey who builds a massive nest in a giant oak tree on the McGregor farm. She captures the attention of the local children, who become determined to observe and protect her from poachers. Her natural migration patterns and instinctual behaviors drive the actions of the human characters who attempt to trace her long journey to Africa.

Jeneba is a 10-year-old girl recovering in a hospital in The Gambia. She dreams of becoming a doctor someday and spends her recovery time reading medical textbooks to further her education. Her life intersects with the Scottish children when she and her family assist in locating a migrating osprey, bridging the geographic divide between their respective communities.

Hamish is a wildlife expert from the local nature reserve who serves as a knowledgeable resource for the community. He brings technical expertise in bird conservation, tracking technology, and veterinary first aid. He actively supports the children's interest in protecting local bird populations and teaches them how to utilize satellite telemetry.

Rob is an 11-year-old boy and one of Callum's closest school friends. Coming from a relatively wealthy family, he proudly displays his expensive mountain bike and enjoys asserting his dominance within his friend group. He harbors inherited resentments toward the McNair family, initially leading him to act with hostility toward any outsiders entering his social sphere.

Mr. McNair is an elderly man living in a dilapidated cottage outside the main village. He raises his granddaughter, Iona, in the absence of her mother. Heavily judged by the surrounding community and struggling with extreme poverty, he remains socially isolated and occasionally turns to alcohol to cope with his difficult circumstances.

Euan is one of Callum's closest school friends, frequently joining him and Rob for outdoor activities. He generally follows Rob's louder personality in social situations but shares the group's growing curiosity about the local wildlife and fishing.

Mr. McGregor is Callum's father, who runs a rural Scottish sheep farm. He is practical and authoritative but willing to lend his resources, physical labor, and community connections to support his son's interest in the natural world.

Mrs. McGregor is Callum's mother, a practical and highly observant woman who runs the household on the sheep farm. She quickly notices when children or neighbors in the community require basic care and readily extends hospitality to those who lack proper support.

Graham is Callum's older brother, who assists with the heavy labor on their family sheep farm. He occasionally complains about his younger brother's antics disrupting his social life but willingly contributes physical labor to help with wildlife observation projects.

Fiona is Iona's absent mother, who left the rural Scottish village for a life in London years prior. The village adults hold deep grudges against her for past financial grievances, leaving a difficult legacy for her family to manage in her absence.

Max is a young American doctor working at a hospital in The Gambia. He provides critical medical treatment to local residents and occasionally extends his expertise to injured wildlife discovered by the villagers in the surrounding swamps.

Mama Binta is a no-nonsense, highly authoritative head nurse at the hospital in The Gambia. She provides direct medical care and strict supervision over her young patients during their intensive recoveries and extensive travels.

The marabout is a respected, blind spiritual leader in the Gambian village. He utilizes intense dreams, inner vision, and ritual smoke to locate missing individuals and creatures, commanding the respect and belief of the local fishing community.