The German title is "Der 21. Juli". It's now available as Ebook in English: "Killing Himmler":
On July 20, 1944, the military conspirators led by Colonel Stauffenberg manage to set off a bomb in Adolf Hitler’s headquarters in Rastenburg, East Prussia. Hitler is instantly killed in the blast.
The plotters move to seize control of the German government, but they do not have sufficient support among the German people, the Wehrmacht leadership or the constituency that really counts – the security apparatus controlled by Heinrich Himmler. They are forced to seek Himmler’s assistance. Himmler, eager to secure his own political survival, agrees to support the new government provided no attempts are made to look into war crimes and abuses perpetrated by the SS.
The new Chancellor of Germany is the conservative politician Carl Friedrich Goerdeler. But Himmler is the shadowy head of the pervasive security service.
The task at hand is to avoid military defeat. Both the conspirators and the SS agree all available resources must be devoted towards preventing military and national catastrophe at the hands of the Allies. And the Germans have an ace up their sleeve. Their nuclear program has been making progress, and in early 1945 they succeed in building an atomic bomb. In May 1945, the Belorussian capital of Minsk is destroyed. Through an informer, the Americans learn that Germany has more bombs available. Faced with the prospect of being attacked with nuclear weapons, the Allies agree to end the war on terms favorable to Germany. It emerges as a third superpower next to the United States and the Soviet Union.
Heinrich Himmler, however, is not satisfied with the status quo. He has maintained a low public profile, but has steadily consolidated his position. His ambition is to settle the accounts with the July 20 plotters, who, he feels, have stabbed Germany in the back. He will eliminate his internal enemies and become the undisputed leader of Germany. Then he plans to deal with Germany’s external enemies once and for all.
In March 1953, Josef Stalin dies. The Soviet Union looks set to become embroiled in internal fighting and confusion over who will succeed him. The time is right for Himmler to make his move.
The American government watches with alarm as Himmler prepares his strike. If he is not stopped, a third world war threatens to engulf a world that has not yet recovered from the previous one. The Americans determine that Himmler must be assassinated.
The man they choose for the job is Knut Werdin, a former SS major, who defected to the Americans in 1945. Werdin and the CIA don’t know that Werdin’s mission has been betrayed by a German informer. The German security service will be waiting for Werdin.
Look for instance at the UK Amazon site: http://www.amazon.co.uk/gp/product/B00UXAVB5K?*Version*=1&*entries*=0