Ada is the protagonist and narrator of the story. She is 10 years old at the beginning of the novel, although she doesn’t know her real age or birth date until near the end of the book when she discovers her birth certificate. Ada is born with a clubfoot. Her handicap brings deep shame to her mother, Mam, who keeps her isolated in the family’s one-room apartment.

Ada is the primary focus of her mother’s physical and verbal abuse. When the story opens, she is malnourished and suffers from rickets, impetigo, and chilblains. She’s accustomed to physical and emotional pain while living with Mam, but under Susan’s care Ada becomes physically healthy and emotionally open to trusting people. She also grows more confident and secure, eventually finding the strength and courage to walk away from Mam. She progresses from the role of the abused, inexperienced victim to the role of the hero—rescuing Margaret, assisting in the capture of a spy, and learning to walk and read. 

Mam is the mother of Ada and Jamie and the antagonist in the novel. She works nights at the pub below the family’s one-room London apartment, then moves to a two-room apartment when she gets a factory job once the war begins.