the Ghastly Ghost at the Shrieking Shack

Hermione does not believe in ghosts, but she does believe in troublemaking students. As Head Girl, it's her job to stop them from engaging in shenanigans, so that's just what she does when she hears about a secret party on Halloween at the Shrieking Shack. But when she arrives, she'll find that there's more to the rumors of a spectre haunting the Shack than simple student gossip.