Katie Bell being attacked by the cursed necklace on the way back from Hogsmeade is easily one of the most horrifying moments in all of Harry Potter, and it comes totally out of nowhere. One minute Ron, Harry, and Hermione are walking back to Hogwarts (a little buzzed), and the next thing they know they're watching Katie be pulled up into the sky and yanked around like a rag doll. Her hair is fanning out unnaturally and she lets out a bloodcurdling scream and it's just not anything you need to see if you'd like to continue sleeping at night. Aside from being genuinely terrifying, this scene is also unnerving as it shows how desperate and sloppy the mystery attacker is becoming.