Rogue Justice — Geoffrey Household

After years on the run, an assassin seeks vengeance against the Nazis

It's been four years since Raymond Ingelram failed to kill Hitler. All it took was a slight change in wind to force his bullet wide and put the entire German secret service on his tail. Ingelram ran to England, where he went to ground in the wilds of Dorset and finally escaped his pursuers. Safe at last, he does the only thing that makes sense: He decides to go back to Germany.
 
War is raging across Europe, and Hitler deserves death more than ever. Infiltrating the Reich with a forged passport, Ingelram is thrown into a provincial prison -- only to be freed by a stray RAF bomb. Wearing a stolen Nazi uniform, he again goes to ground . . . and forms a plan to tear Nazi Germany apart from the inside out.