Twenty-five years after the end of the war, Noah Ainsworth is still preoccupied with those perilous, exhilarating years as a British SOE operative in France. A head injury sustained on his final operation has caused frustrating gaps in his memory—in particular about the agent who saved his life during that mission gone wrong, whose real name he never knew, nor whether she even survived the war.

Aleen Cust has big dreams. And no one―not her family, society, or the law―will stop her. Born in Ireland in 1868 to an aristocratic English family, Aleen knows she is destined to work with animals, even if her family is appalled by the idea of a woman pursuing a veterinary career. Going against their wishes but with the encouragement of the guardian assigned to her upon her father’s death, Aleen attends the New Veterinary College in Edinburgh, enrolling as A. I. Custance to spare her family the humiliation they fear.

Londoner Madeleine Grant is studying at the Sorbonne in Paris when she marries charismatic French journalist Giles Martin. As they raise their son, Olivier, they hold on to a tenuous promise for the future. Until the thunder of war sets off alarms in France. Staying behind to join the resistance, Giles sends Madeleine and Olivier to the relative safety of England, where Madeleine secures a job teaching French at a secondary school. Yet nowhere is safe. After a devastating twist of fate resulting in the loss of her son, Madeleine accepts a request from the ministry to aid in the war effort.

July, 1940. Blitz-ridden London: Marnie Fern’s life is torn apart when her grandfather is killed in an air raid. But once she discovers that he’d been working undercover as a radio operative – or pianist – for the Dutch resistance, Marnie knows she must complete his mission – no matter the cost. Nazi-occupied Amsterdam: At the other end of the wireless, fellow pianist Corrie Bakker is caught in a dangerous game of cat-and-mouse as she desperately tries to keep her loved ones out of the line of fire – even if it means sacrificing herself.

Maia D’Aplièse and her five sisters gather together at their childhood home–a fabulous, secluded castle situated on the shores of Lake Geneva–having been told that their beloved adoptive father, the elusive billionaire they call Pa Salt, has died. Each of them is handed a tantalising clue to their true heritage–a clue which takes Maia across the world to a crumbling mansion in Rio de Janeiro in Brazil . . .