The Black Duke (1963)

Cesar Borgia--a cardinal in the Catholic church, a confidant of the Pope and a member of one of the wealthiest and most powerful families in 16th-century Italy--must deal with a host of political and personal crises. He is having problems with his mistress, and members of a secret society called The Black Carnation are out to assassinate him.

Unfortunately the movie The Black Duke is not yet available on HBO Max.