During his time as head of the Sicherheitspolizei (Security Police) in Rome, Kappler organized the round-ups of thousands of innocent victims, oversaw raids on Jewish homes for looted valuables, and was a key figure in transporting Italian Jews to Nazi death camps.

Father Pietro Antonelli is a combination of several different Vatican officials who personally knew Kappler, the most significant of whom was Monsignor Hugh O'Flaherty (who appears in the television film The Scarlet and the Black).

One prisoner, a deserter from the Austrian army who had pretended to be an Italian, was allowed to live, as a citizen of the Reich; and he was the only witness to tell the tale of the courageous behaviour of the Resistance priest, Don Pietro Pappagallo, who blessed those about to be killed, before he himself met his fate.

Kurt Mälzer is shown throughout the film giving direct orders to SS units and personally supervising the buildup to the massacre organized by Kappler.

Then, on Nationwide TV in the 1990s, ABC News reporter Sam Donaldson found and confronted him about the massacre, leading him to say he "followed orders".

In reality, he stood trial and was found guilty of killing Italian Jews as part of the operations in Italy: when he became sick, his sentence was reduced and he was released in 1971.