Italy, 1943: With war blazing through Europe, nowhere is entirely safe—not even the remote hills of the Tuscan countryside. It's here that Italian partisans, including thousands of women, risk their lives to provide Jewish refugees with an escape route to Switzerland. And it's here, too, that Gianna Conti travels to join the Italian Resistance in the wake of her brother Matteo's death at the hands of German soldiers. Her father has been hiding Jewish refugees on their family's vineyard in Chianti, but now Gianna is bringing the fight directly to the enemy.

While delivering weapons and intelligence for partisans, Gianna meets Tazio Napoli, an American working undercover for the Office of Strategic Services. Despite the growing odds of discovery, Gianna and Tazio conduct high-risk missions to sabotage German operations. With the aid of Tazio's OSS codebook, they encrypt secret messages to each other while apart, hiding them at a dead drop in an abandoned mine.

But as the Allies steadily fight their way toward Florence, occupying German forces grow more desperate, leading to a shocking, unthinkable act of vengeance. And Gianna's fate will rest upon her cunning, her resilience, and her willingness to keep hope alive, even through the decades that follow . . .