Fritz Lang used the novel by Geoffrey Householder called Rogue Male to make his amazing film "Manhunt."
Rogue Male is a BBC production based on the same very entertaining and thoughtful suspense novel. If you can get a cheap copy from amazon, it would be fun to read.
An English big-game hunter wants to see whether it might be possible for him to kill Hitler. This is in 1939, as people are beginning to realize that Hitler is having a malevolent effect throughout the world.
What I liked about the Lang film and the novel is that the hero of this story comes from the upper class in England and was never taught how to be a real 'moral' actor in the world. Everything is a game to him (and his class). So at first he does not perceive killing Hitler as a moral act - it is a game. This is one reason why he fails.
However, he undergoes a moral transformation as the story unfolds and by the end of the novel he is ready to truly kill Hitler.
I have to be honest - I'll watch this BBC version soon - I don't know how good this film is. I hope you enjoy it though.
See the film here:
https://www.youtube.com/watch?v=yMtGmGa8KZ0