Cassandra was a figure in Greek mythology who received the gift of prophecy with the curse that no one would believe her. Compare Cassandra to characters in Night.
In Greek mythology, Cassandra was the daughter of King Priam of Troy. She was given the powers of prophecy by Apollo as long as she did what he wanted. When she refused, he cursed her by making sure her prophecies were never believed. She accurately predicted the fall of Troy but was ignored by the Trojan leaders. The two characters that communicate Cassandra like warnings in Elie Wiesel's memoir Night are Moshe the Beadle and Madame Schächter. In the opening section of the book Moshe the Beadle is deported as a foreigner and witnesses the Nazi atrocities which take place in the forest of Galicia. He miraculously escapes and returns to Sighet to warn the Jews of what he had seen. The horrors he describes, however, are too terrible for anyone to believe. Even Elie doesn't believe him. The townspeople simply think he has a wild imagination and has gone crazy.
In section two, Elie is in a train car with Madame Schächter and her son after being deported from Sighet. The train is bound for Auschwitz. Throughout the trip the woman erupts into screaming about seeing fire and flames coming from a furnace. When the men on the train look out the windows there is nothing. They hit her and tie her up but she continues her raving. Like Moshe, her warnings fall on deaf ears. At one point the Jews believe that Auschwitz is simply a labor camp where the conditions were good and families would not be split. Of course, this information proves false and when they reach Birkenau, the reception center for Auschwitz, the flames which Madame Schächter had predicted come into full view. The flames come from the crematories of the concentration camp where the Germans are burning the dead bodies of the Jews who have been exterminated.