Shortly after you set off, Ron asks you if you have a map.
'Er, no. Was I supposed to have one?'
'Well yeah. Mind you, I don't have mine either.'
'We can double back,' you decide - just as the staircase beneath your feet starts moving. Ron looks panicked as he tries to remember what corridor you just left behind. The staircase stops, and you get off, but Ron does not. It carries him to the other side.
You stare at each other. 'How do I get across?'
You're not quite sure. You advise Ron to get back on the staircase; but when he does, he ends up on a different floor. Then when you get on the staircase, you find yourself two floors above him. You stand there, wondering what on earth to do, when you hear a voice behind you.
'I say, hello there!'
You turn round. It's a painting of a man in a big cloak.
'I'd catch the next one if I were you,' he said. Count to twelve, and it should get you down.'
You give teh man the thumbs up.
'Er, thanks,' you say, as the next staircase rumbles into position. You step on. Sure enough, you soon find yourself on the same floor as Ron. He grimaces at you.
'How'd you get down?'
'A painting told me how to do it.'
Ron raises his eyebrows. 'Oh, right. Maybe we can ask one of them directions to... where is it?'
You dig the timetable out of the pocket of your robes. 'Transfiguration, Professor McGonagall, 9am.'
Ron whirls round to face the portrait behind him - a squat little woman whom you recognise as Violet from one of the films. 'Excuse me,' he says, scratching his nose. 'Would you mind helping us?'