Valkyrie is a movie about a bunch of good Germans who plot to assassinate Adolf Hitler during World War II. If you are spoiled by my giving away the ending-- that they are unsuccessful-- then you probably aren't the type that would be interested in a historical thriller in the first place. It ends with a montage of all the protagonists being executed, or executing themselves.
The movie itself is well-made enough, but here's a different question: Who wants to watch a bunch of people fail to kill Hitler?
I hear the upcoming Quentin Tarantino movie, Inglourious Basterds, is about a bunch of people who plot to kill Hitler and actually succeed. I find the whole concept of it absolutely delicious. Now that's the kind of thing I'm interested to see.