Can two orphans who only have each other survive a world at war when they discover the shocking truth of their past?

England, 1943: Eight-year-old twins Molly and Jacob are no longer safe at home. Night after night wailing bombs and screeching planes skim the rooftops overhead. With no other choice, their mother, Martha, sends them to the safety of the countryside—but not without passing on a dangerous secret. Fearful of never seeing her children again, Martha gives Jacob a letter, telling him to only read it if they are in danger.

In the country, Molly and Jacob struggle to adjust to life with strangers. But then the unimaginable happens. An explosion kills Martha, leaving the twins all alone in the world. Faced with the grim reality of life in an orphanage, the time has come for Jacob to honor his mother's last wish. But are its secrets enough to change the course of their tragic fate? Because Jacob believes that so long he and Molly are together, they can survive anything.

And the letter may be what tears them apart.