Music to go with the Article
Sometimes people just won't believe you.
You try your hardest to tell someone that your parents are actually super villains and that you need their help to bring them to justice, or that aliens have landed in your backyard and are now plotting to take over the world, or that the nice grandpa in the flat above you is in fact the God of Madness, but the authorities look at you like you are crazy and send you packing. What's a lone protagonist to do?
A common staple of Disney and children's films, where the Kid Hero stumbles upon an evil conspiracy or a criminal ring and their parents and the police refuse to listen. The only thing to do is to save the day yourself, with PG heroics and Scooby-Doo style.
If the protagonist trying to report the situation works for someone who can actually do something about it, such as the FBI, it's not so much that s/he isn't believed, but AUthorties will tell him/her that it isn't worth it to expend resources "on a hunch".
If a minor character finds out and tries to tell someone that the guy next door is secretly a Super Hero, they won't be believed, because who would ever think that that foppish playboy could really be the dark, grim Super Hero? Often though, it's because they're horrible at wording it so it sounds genuinely insane.
Sometimes Character A actually asks what's going on and, when given the true-but-bizarre explanation by Character B, responds "Well, if you don't want to tell me, just say so".
The title comes from Cassandra from Classical Mythology, theater, and literature, as featured in The Iliad, The Odyssey, the lost epics of the Trojan Cycle, The Aeneid, and many others!
Cassandra is the high preist of the Trojans and warned them about the Trojan Horse but none of them listened.
Apollo put a curse on her so that people would never believe her prophecies because she falsely promised to marry him to get her power.