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. Bound together by the invisible wires of their radios, the two women lead parallel lives in their home cities, as both are betrayed by those they trust the most. But when the Nazis close in on one of them, only the other can save her.

Norway, 1942: War rages, and, under cover of darkness, Rumi Orlstad and her fellow resistance fighters smuggle British agents, fugitives and supplies across the North Sea into Nazi-occupied territory. One night, when he braves a storm to complete an ill-fated mission, Rumi’s fiancé is lost to the dangerous waters. Broken-hearted, she withdraws from the clandestine group, vowing never to let her loved ones put themselves in the line of fire again. But months later, Rumi stumbles across a Nazi secret that lays Hitler’s plans for Norway bare, and she knows she has no choice but to risk her life for her country once more.

Berlin, 1938: It’s the height of summer, and Germany is on the brink of war. When fledgling reporter Georgie Young is posted to Berlin, alongside fellow Londoner Max Spender, she knows they are entering the eye of the storm. Arriving to a city swathed in red flags and crawling with Nazis, Georgie feels helpless, witnessing innocent people being torn from their homes. As tensions rise, she realizes that she and Max have to act --- even if it means putting their lives on the line. But when she digs deeper, Georgie begins to uncover the unspeakable truth about Hitler’s Germany --- and the pair are pulled into a world darker than she ever could have imagined.