Stephen made a noise of disgust in his throat as we descended the Marble Staircase into the Entrance Hall.

'I mean – it's pure censorship!' fumed Kevin, not bothering to keep his voice down. 'How many proclamations have we seen on that noticeboard in the last month? When they say power corrupts, they were clearly talking about her!'

'I can't stand her,' agreed Stephen, his face uncharacteristically dark.

'First she basically cancels Defence Against the Dark Arts, and now she's breaking up societies and punishing people for asking about basic information. It's gone beyond ridiculous,' continued Kevin.

We reached the bottom of the Marble Staircase to find our way impeded by Argus Filch, who was leering unpleasantly at us.

'Not insulting our High Inquisitor, I hope?' he said, glaring at Kevin through his bloodshot eyes.

'No, never!' cried Stephen with heavy sarcasm.

I flashed him a warning glance. It would do no good to get into an argument with Filch. We'd all just end up in detention. But Stephen wasn't paying me any attention.

'Why would we ever criticise the Ministry puppet who swaggers into our school and plonks herself down at the High Table in order to issue one stupid law after another?' he continued, his voice raised. 'She's an absolute delight.'

The crowd of students heading towards the Great Hall had stopped in order to listen to their exchange. I groaned inwardly and raised my eyes to the heavens.

'You'll be sorry you said that, boy,' growled Filch, his jowls aquiver. 'Slandering a member of staff … tut, tut. I expect that deserves at least a double detention, but I shall have to consult with Professor Umbridge. The three of you can expect to hear from her later today.'

He smiled unpleasantly and hobbled off through the crowd. The students on either side of us exchanged smirks before moving on again.

'Why did you have to bait him?' I demanded of Stephen.

He shrugged as we made for the Great Hall with everyone else. The weak October sunlight streamed through the windows above the house hourglasses.

'I was angry. And I'm sick of Filch sliming around the school looking for trouble.'

'Well, because of you, the three of us will probably be stuck in detention this weekend. Thanks a bunch,' said Kevin bitterly.

Stephen ignored him. We passed through the golden doors into the Great Hall and grabbed three empty seats at the Ravenclaw table, just in time for lunch to appear on the empty plates. As I tucked into my food, I noticed Kevin gazing thoughtfully at his plate, his fork tracing circles in the butter.

'Something on your mind?' I asked, poking him in the arm to bring him out of his reverie.

'Hm? Oh, well – not really … I was just thinking …' he said slowly.

'Careful, there,' quipped Stephen.

Kevin gave him a withering look.

'I was just thinking about what Terry and Michael were saying about that new group Potter has set up … you know – the one where he teaches defence?'

'What about it?' I asked, taking a sip of hot tea.

'I think we should give it a go,' said Kevin, looking between me and Stephen.

I raised my eyebrows and considered it for a few moments. A few seats to my left, Ginny Weasley had floated over from the Gryffindor table to sit with Luna Lovegood.

'Yeah, I'd be game,' I said after a moment. 'It could be a good idea.'

'Me too,' said Stephen firmly. 'Anything to get back at that old toad.'

Kevin grinned.

'Excellent. That settles it; we're joining an illegal student organisation!'