Myrtle was, officially, a master of disguise. She had picked the best spot on the entire sixth floor to hide and no one had caught her. Not even that itty-bitty Ravenclaw girl had seen her, not even when she had hid right behind the same pillar Myrtle was hiding behind. True, Myrtle had the ghostly advantage of being see-through and all, but still. She'd been a good girl and hadn't even giggled at the Fat Friar or anything.

They were all too worried about their 'secret mirror' to bother about Myrtle anyway. Good - she really didn't want to face the wrath of the Bloody Baron when he discovered she had been the one to reveal its location.

And now that all the other ghosts had floated away to have a 'secret meeting', Myrtle could float back to bothering the Prefects. It was the best way to spend an eternity of free time, after all. Barty Squid was much more boring company than the students of Hogwarts.

Myrtle floated out from behind her pillar, looking left, then right very carefully before floating anywhere else. She thought the coast was clear and then started bounce-floating her way to the nearest staircase.