I have written two books on this. A factual history of the German Resistance, called AN HONOURABLE DEFEAT, published in the UK by Heinemann and in the USA by Henry Holt. It is now reissued as an eBook by Endeavour Press, and is available from them or via Amazon.
When I was researching that book, I came across Arthur Nebe, a career policeman who rose to be head of the German equivalent of the CID. He was an early member of the Nazi Party, but became disaffected with Nazism when Hitler abandoned any pretence of socialist principles. Nebe was successfully recruited to the Resistance and worked for it until he was betrayed following the failure of the Stauffenberg Bomb Plot in July, 1944. To maintain his position and thus help the Resistance he had to perform many tedious duties as a Nazi, however: the question remains: how much do the ends justify the means?
There is very little information on Nebe, only one dubious biography. I decided to adapt what material I had and write a novel about him. It took me ten years but at last it is available and I am very proud of it. It has recently been published both as a paperback and an eBook by Endeavour Press, and is available from them or Amazon. I’d be very interested to hear what people think of it. Links to purchase these are below:-