The Spy with the Red Balloon (The Balloonmakers)

Siblings Ilse and Wolf hide a deep secret in their blood: with it, they can work magic. And the government just found out.

Blackmailed into service during World War II, Ilse lends her magic to Americas newest weapon, the atom bomb, while Wolf goes behind enemy lines to sabotage Germanys nuclear program. Its a dangerous mission, but if Hitler were to create the bomb first, the results would be catastrophic.

When Wolfs plane is shot down, his entire mission is thrown into jeopardy. Wolf needs Ilses help to develop the magic that will keep him alive, but with a spy afoot in Ilses laboratory, the letters she sends to Wolf begin to look treasonous. Can Ilse prove her loyaltyand find a way to help her brotherbefore their time runs out?