As World War II comes to a close, a German teenager arrives in America, ostensibly to start a new life away from the chaos in her homeland.  In order to flee, Eva Gerst has made a deal with the devil.  She and her mute best friend have been allowed to leave the country only because Eva knows an important secret.  She holds the key to Project Bluebird, a horrifying concentration camp experiment, the results of which are so powerful that both the Americans and the Germans would do anything to control it.  Eva's determination to keep it away from them is just as strong, but it's not power she's seeking.  She desires only one thing—justice.  No matter what it takes, she will track down the escaped Nazi who designed the horrific experiment.  And then, she'll kill him.

In an alternating storyline, Inge von Emmerich is living in war-torn Germany a year earlier.  The daughter of a powerful Nazi couple, she's been thoroughly indoctrinated.  It's not until her eyes are opened to the atrocities being committed by the regime that she realizes just how wrong her family's view is—and how involved her father is in appalling acts against their Jewish countrymen.   

As the girls' stories collide, they will come together to take down a monster in a desperate race to settle a score, get justice, and not just clip Bluebird's wings, but destroy it forever.