I got very interested in the plot after reading
The Berlin Diaries 1940-1945 by Marie Vassiltchikov. It's one of a kind in so many ways, I'm sure to be disappointed by
Valkyrie, but I have to see it.
You can read a little about the author
here. "Vassiltchikov's diaries are the only known first-hand account of the July 20th Plot to kill Adolf Hitler. In addition, her description of the repeated bombing of Berlin is considered one of the best testimonies of that event."
"In addition, her [Missie's] diaries detail the bombing of Berlin, the daily life of what remained of Berlin's cosmopolitan pre-war nobility and intelligentsia, and her own journey from privilege to near-death at the end of the war."
If you're not going to see the movie, give yourself a treat, and read Missie's book!