you must tell the external Italian professor that if it is not in the thesis and in the program, then he shouldn't ask you for it
If he is stubborn and still wants to ask you, then tell him interesting things, not the plot... let's look at a few things:
1) the plot of the tetralogy is complex; it is unlikely that you will start to remember it without having ever truly studied or listened to it. If that professor is an Italian teacher, however, he will be pleased to know certain things. For example, that the libretto for the 4 operas was written by Wagner himself, a very rare thing for the time, considering that writing a libretto is something for a poet, not a composer. The sources of the Wagnerian Tetralogy are essentially two: the Old Norse poem (in the Old Norse language, an ancient Germanic language) "Edda" by Snorri Sturluson ( http://it.wikipedia.org/wiki/Edda_in_prosa ), which has a long part regarding Germanic cosmogony, and the medieval novel "Nibelungenlied" (the Song of the Nibelungs http://it.wikipedia.org/wiki/La_canzone_dei_Nibelunghi ), by an unknown author, which takes up the so-called Volsunga Saga (http://it.wikipedia.org/wiki/Saga_dei_V%C3%B6lsungar ) and brings it to a tragic conclusion. This passion of Wagner's for Germanic mythology is typical of the cultured German environment; in short, it is a re-presentation of pre-romantic and romantic themes of the exaltation of ancient history and ideals of heroism, and explicitly refers back to Goethe, so much so that the libretto is in a clear Goethian style. Instead of learning the plot, which is extremely complicated, memorize these things: the literary sources and the "aesthetic-literary" landscape.
2) Consequently, anyone who says that within the Wagnerian Tetralogy there are themes that anticipate Nazism is simply IGNORANT. The continuous pairing of Wagner-Hitler is annoying, really... Richard Wagner died in 1883! The point is that his is the first truly "German" opera, with heroic themes that LATER became dear to the Third Reich but which already exist in medieval Germanic literature... The real links between Hitler and Wagner occurred through WINIFRED WAGNER, wife of Siegfried Wagner (Richard Wagner's son). In short, Richard Wagner opens a theater and founds the Bayreuth Festival; then he dies, leaving management to his son Siegfried (who was gay) who marries Winifred very late. She lives through the entire period of the Reich and becomes a fervent supporter of Hitler and Goebbels, who in turn subsidize the Bayreuth Festival with huge amounts of money. It is DURING THIS PERIOD that the connection between Wagner's music and the Nazi regime is born; therefore, it is not Richard Wagner's "fault" (who was actually an anarchist...) but that of his descendants (not all of them, though...).
3) Wagner and antisemitism... it is a complex issue that often becomes an urban legend. Wagner was an antisemite. There is no doubt about this. And so were Liszt, Schumann, and probably millions of other people. Antisemitism was very common in the 1800s and before. It was especially common in politics, where the first racist sociological theories began to develop—those that analyze historical movements as consequences of the race to which the inhabitants of a state or group belong. If the German economy was doing poorly, or if music was doing poorly, or sports, or whatever, there was a tendency to blame a race, an entire ethnic group. And the Jews, who were present almost everywhere, were the most affected ethnic group. Wagner also wrote a famous treatise, "Jewishness in Music," and his contemptuous judgments of Mendelssohn have gone down in history (we have discussed this on the forum somewhere). But talking about Wagner's antisemitism in relation to the Holocaust means mixing apples and oranges, in my opinion... there are at least 70 years between the two things!
4) So, if you have a bit of courage (I know it is hard to have it in adulthood), when the Italian professor asks you "tell me about Wagner and Hitler," the first thing you must say is "Wagner died in 1883. Limiting Wagner's figure to what the Nazis thought of him is incorrect, especially historically. And this too is one of the violences that the Nazi regime committed against GERMAN culture."