Time Traveler

I've succeeded once again. It is crystal clear now. I have a gift for cryptanalysis and I am sent through history to aid at critical turning points. It is time for me to help save the world.

I set the dial to May 1943 and the location to Hut 3, Bletchley. I know other Americans will be there. I press the button and the machine whisks me away. I materialize in a long hallway. There is a single door at the far end.