No one besides Sally and her father knows there is a nuclear device planted somewhere because Sally's father only told Sally and Sally hasn't told anyone. So no one would have any reason to tell Mother Teresa or Mohandas Gandhi to convince the Hitlerites to torture Sally for the information. Not to mention the button that saves Europe and Africa is not even applicable in this circumstance since Sally would have pressed it herself if the city that was in danger was located in Europe and/or Africa. The scenario inherently prevents us from taking action due to our ignorance derived from the premise and thus lacks an ethical question, normative or otherwise, for us to consider. /s edit: typo