Margot is an 11-year-old girl living in an isolated Cumbrian cottage with her mother. She initially accepts her family's grim diet of lost travelers, though she soon begins to experience unsettling pangs of conscience. Socially isolated and struggling academically, she retreats into her imagination and crafts spells from cockleshells and hemlock root. She endures harsh treatment at home while trying to figure out her own moral boundaries.

Ruth is a tall blonde woman who lives completely off the grid. She possesses a ravenous appetite for lost hikers, whom she lures to her cottage to butcher and consume. She exercises severe control over her daughter, demanding total obedience and dismissing physical abuse as affection. She often wears thick red lipstick to hide her plaque-covered teeth and dresses in the clothing of her victims.

Eden is a confident woman with silver-streaked blonde hair who arrives at the cottage claiming to have a blown tire. Rather than becoming another meal, she quickly forms an intense bond with Ruth. She makes herself at home in the cottage, shifting the household dynamics and physically displacing Margot from her mother's side.

Steve is a heavily wrinkled bus driver who sings folk songs on his daily route. He provides a rare source of adult kindness in Margot's life, regularly checking on her well-being when she looks tired or bruised. He encourages his passengers to stay on a righteous path and pays close attention to the vulnerable children in his care.

Abbie is a compassionate classmate who wears a green ribbon in her hair. As the daughter of the local gamekeeper, she provides Margot with unconditional friendship. She actively supports Margot in class and rejects the hostile behavior of the school bullies.

Papa is Margot's absent father, known to her mostly through old photographs and clothes packed away in boxes. According to Ruth, he walked out because he wanted a quiet wife and could not accept Ruth's volatile nature. He serves as an idealized figure in Margot's mind.

The strays are various lost hikers, travelers, and marginalized individuals who stumble upon the isolated cottage. Often injured by glass and nails deliberately scattered on the road, they seek refuge with Ruth. They serve as the primary food source for the household.

Mike is the local gamekeeper and a married father. He engages in a passionate affair with Ruth, visiting the cottage in the afternoons. He entertains his child with local folklore and promises Ruth that he will leave his wife for her.

Patrick is a cruel schoolmate who frequently targets Margot. He embodies the hostility Margot faces outside her home, often calling her a freak, showing her obscene videos, and physically threatening her on the bus.

Mr. Hill is a math teacher at Margot's school. He grows impatient with Margot's inability to grasp ratios and fractions. He notices physical marks on Margot but chooses to ignore them to avoid dealing with the complication.