It's 1962, and the world is teetering on the brink of nuclear war. But daily life must go on. South London girl Celia Duchesne longs for a career but with no means, connections, or qualifications, she spends her days at the till of a dusty antiquarian bookshop on the Strand, unable to see a way out. The day a handsome American walks into the shop, she thinks she might have found it. Just as the excitement of a budding relationship engulfs her, she learns a devastating secret that draws her into the murky world of espionage. Twenty years prior, nineteen-year-old Anya Moreau was dropped behind enemy lines to aid the resistance in occupied France, sending messages back to London via wireless transmitter. When she was cruelly betrayed and handed over to the Nazis, evidence of her legacy and the truth of her actions were buried by wartime injustices. As Celia learns more about Anya, and her unexpected connection to the undercover agent, she becomes increasingly aware of furious efforts, both past and present, to protect state secrets, at all costs. With her newly formed romance taking a surprising turn and the world's superpowers on the verge of nuclear annihilation, Celia must risk everything she holds close to her heart, in the name of justice.