When a Quaker Kindertransport chaperone is murdered in the East End of London, Britain's counterintelligence spymaster tasks Olivia Denis to join the group rescuing children from Nazi Germany. Olivia must find not only a killer, but a traitor relaying sensitive material to the enemy. Once they reach Berlin, Olivia discovers she must rescue the family of an imprisoned British spy before she leaves the next day. An attack convinces Olivia the family's two young sons are in grave danger, but where to hide them? Can she protect the boys before they become the traitor's next victims?