The movie is based on Alexander Ramati's book called The Assisi Underground. Ramati learned of what happened when he was in Assisi after the liberation in 1944 and promised to chronicle the story of how a simple Franciscan priest and a local bishop concealed Jews during the German occupation.
The movie takes liberties with the story and adds elements (such as looking for a Italian Jewish scientist who knew Enrico Fermi) that were not there. Some action sequences did happen in the book (the train scene where British planes bomb the area) while some were altered. Colonel Muller and the SS Captain reflect their characters for the most part. It does relate correctly though the bravery of everyone working together to help save the Jews. But if you want the full story, read the book as it will give a lot more details than depicted in the movie.
The movie takes liberties with the story and adds elements (such as looking for a Italian Jewish scientist who knew Enrico Fermi) that were not there. Some action sequences did happen in the book (the train scene where British planes bomb the area) while some were altered. Colonel Muller and the SS Captain reflect their characters for the most part. It does relate correctly though the bravery of everyone working together to help save the Jews. But if you want the full story, read the book as it will give a lot more details than depicted in the movie.