i think the base plot is sound enough, a few thoughts though. 1.) Like others have said, you need to make georg younger. He is way to old in you original write-up. 2.) It may be interesting to consider a plot point where Georg is in the Nazi Army because he came up through the Hitler Youth. This means that he was put in by his parents (or because he was an orphan), and finds a sense of belonging with the other boys from it, but he may not actually believe the hate that they spew. It could end up creating a really great sense of inner conflict for him resulting in him eventually abandoning his unit and going to save Gineke. If you want some interesting historical context here i suggest you read a bit on "the man who didn't salute". The events are about man who joined the Nazi Party hoping that it would lead to work. While in the party he fell in love with a Jewish Girl he wanted to marry, which of course the Nazi's would not allow. So at a famous Rally he is photographed in a very famous photo as the only person not saluting Hitler. He ended up being placed in a work camp for 2 years and his fiance was killed in a death camp. So there is reality in your story.
I recently discovered this, which I'm at present obsessed with in terms of outlining my plots: http://blog.janicehardy.com/2012/05/best-advice-on-plotting-ive-ever-heard.html
Thank you everyone for your wonderful suggestions. It really helped me a lot! I will start my writing soon but before I need to do some research first. I wish you all best of luck. Cheers, F.L
