Vintage Vonnegut: Mother Night

Whilst awaiting trial for war crimes in an Israeli prison, Howard W. Campbell Jr sets down his memoirs on an old German typewriter. He has used such a typewriter before, when he worked as a Nazi propagandist under Goebbels. Though that was before he agreed to become a spy for US military. Is Howard guilty? Can a black or white verdict ever be reached in a world that's a gazillion shades of grey?