Valkyrie by Philipp Freiherr von Boeselager
 

This is a very interesting book by the last then surviving member if the various German army plots to kill Adolf Hitler. It is by an aide of Major General Henning von Tresckow.

If you have seen the movie of the same name Kenneth Branagh plays Major General Henning von Tresckow.

Some information about this man-- http://en.wikipedia.org/wiki/Philipp_von_Boeselager