In a time of war, danger lurks beneath the water—and in the depths of the human heart

As the German war machine devours the Netherlands, the only way Cilla van der Zee can survive the occupation is to do the unthinkable—train to become a spy for the Nazis. Once dispatched to Britain, she plans to abandon her mission and instead aid the Allies. But her scheme is thwarted when naval officer Lt. Lachlan Mackenzie finds her along the Scottish shore and turns her in to be executed.
Yet perhaps she is more useful alive than dead. British intelligence employs her to radio misleading messages to Germany from the lighthouse at Dunnet Head in Scotland—messages filled with naval intelligence Lachlan must provide. If the war is to be won, Lachlan and Cilla must work together. But how can he trust a woman who arrived on his shores as a tool of the enemy—a woman certain to betray both him and the Allied cause?