Exhilarating read set at the dawn of WW2; a young Jewish girl becomes a spy and infiltrates Nazi academy

Orphan Monster Spy - Matt Killeen

This was such an exhilarating read and a book that really is so different from anything else in the YA genre right now; I read this in its entirety during one day of the '24in48' Readathon this weekend, I absolutely couldn't put it down.
Set at the dawn of World War 2, Sarah has just witnessed her mother's murder, after fleeing their home because of Jewish round-ups, and somehow lands in the care of a British spy, Captain Floyd. He takes her under his wing, who realizes that her long blond hair, pale skin, and blue eyes, make her look less like the Jew that she is, and more like the Aryan Elite that makes her a perfect infiltrate at the Rothenstadt boarding school, an academy for Nazi general's daughters. Now under a new identity as Ursula Haller, Sarah is suddenly on a mission to gather secrets from within, and she is thrown among the wolves where some of the nastiest discipline happens in the name of the Fuhrer.
Every day, it feels like there's a danger of her identity being discovered, and even her recurrent nightmares threaten to give her away; throughout the book she has them, and she also continuously 'speaks' to her 'Mutti' for strength, although she has passed away. You constantly get the feeling it's very difficult knowing how hard it is to get through each day without a person to confide in, with no one to trust.
The entire book is built around the character Sarah/Ursula, and author Matt Killeen depicts a young teen who has to be very strong, makes hard decisions, has to be very brave, and at times, wishes she could just break down, and in many ways, is still so so immature. I would imagine this to be the way it was for many children forced to grow up in war time (regardless of circumstance).
While I don't know how many readers will go into this with extreme detail of World War 2 (being from Britain, having a WW2-obsessed dad I know plenty, believe me), I had SO much anxiety for Sarah throughout the book. I couldn't trust a single, sodding character! I fully realize that this is YA, and Killeen wasn't about to turn this any scarier, but it did get me wondering how much worse things could have turned... There's a lot more war left, after the point the book ended too! More adventures for this spy?
I'm going to say immediately that it will be definitely be in contention for a top ten spot for me this year. Any book that sucks me back into a time period where you think about how your very existence could be always in questionable danger, makes such a mark on me, and I hope others reading really felt that too. It made such a change to read a novel about this era for this age group. Put it on your TBR, everyone!!!