'Excellent!' he said. 'Very well, Potter, you may go!'

As Harry passed Umbridge beside the door, their eyes met. There was a nasty smile playing around her wide, slack mouth, but he did not care. Unless he was very much mistaken (and he was not planning on telling anybody, in case he was), he had just achieved an 'Outstanding' OWL.

On Friday, Harry and Ron had a day off while Hermione sat her Ancient Runes exam, and as they had the whole weekend in front of them they permitted themselves a break from revision. They stretched and yawned beside the open window, through which warm summer air was wafting as they played wizard chess. Harry could see Hagrid in the distance, teaching a class on the edge of the Forest. He was trying to guess what creatures they were examining — he thought it must be unicorns, because the boys seemed to be standing back a little — when the portrait hole opened and Hermione clambered in, looking thoroughly bad-tempered.

'How were the Runes?' said Ron, yawning and stretching.

'I mis-translated ehwaz, ' said Hermione furiously. 'It means partnership, not defence, I mixed it up with eihwaz. '

'Ah well,' said Ron lazily, 'that's only one mistake, isn't it, you'll still get — '

'Oh, shut up!' said Hermione angrily. 'It could be the one mistake that makes the difference between a pass and a fail. And what's more, someone's put another Niffler in Umbridge's office. I don't know how they got it through that new door, but I just walked past there and Umbridge is shrieking her head off — by the sound of it, it tried to take a chunk out of her leg — '

'Good,' said Harry and Ron together.

'It is not good!' said Hermione hotly. 'She thinks it's Hagrid doing it, remember? And we do not want Hagrid chucked out!'

'He's teaching at the moment; she can't blame him,' said Harry, gesturing out of the window.

'Oh, you're so naive sometimes, Harry. You really think Umbridge will wait for proof?' said Hermione, who seemed determined to be in a towering temper, and she swept off towards the girls' dormitories, banging the door behind her.

'Such a lovely, sweet-tempered girl,' said Ron, very quietly, prodding his queen forward to beat up one of Harry's knights.

Hermione's bad mood persisted for most of the weekend, though Harry and Ron found it quite easy to ignore as they spent most of Saturday and Sunday revising for Potions on Monday, the exam which Harry had been looking forward to least — and which he was sure would be the downfall of his ambitions to become an Auror. Sure enough, he found the written paper difficult, though he thought he might have got full marks on the question about Polyjuice Potion; he could describe its effects accurately, having taken it illegally in his second year.

The afternoon practical was not as dreadful as he had expected, it to be. With Snape absent from the proceedings, he found that he was much more relaxed than he usually was while making potions. Neville, who was sitting very near Harry, also looked happier than Harry had ever seen him during a Potions class. When Professor Marchbanks said, 'Step away from your cauldrons, please, the examination is over,' Harry corked his sample flask feeling that he might not have achieved a good grade but he had, with luck, avoided a fail.

'Only four exams left,' said Parvati Patil wearily as they headed back to Gryffindor common room.

'Only!' said Hermione snappishly. 'I've got Arithmancy and it's probably the toughest subject there is!'

Nobody was foolish enough to snap back, so she was unable to vent her spleen on any of them and was reduced to telling off some first-years for giggling too loudly in the common room.

Harry was determined to perform well in Tuesday's Care of Magical Creatures exam so as not to let Hagrid down. The practical examination took place in the afternoon on the lawn on the edge of the Forbidden Forest, where students were required to correctly identify the Knarl hidden among a dozen hedgehogs (the trick was to offer them all milk in turn: Knarls, highly suspicious creatures whose quills had many magical properties, generally went berserk at what they saw as an attempt to poison them); then demonstrate correct handling of a Bowtruckle; feed and clean out a Fire Crab without sustaining serious burns; and choose, from a wide selection of food, the diet they would give a sick unicorn.

Harry could see Hagrid watching anxiously out of his cabin window. When Harry's examiner, a plump little witch this time, smiled at him and told him he could leave, Harry gave Hagrid a fleeting thumbs-up before heading back to the castle.

The Astronomy theory paper on Wednesday morning went well enough. Harry was not convinced he had got the names of all Jupiter's moons right, but was at least confident that none of them was inhabited by mice. They had to wait until evening for their practical Astronomy; the afternoon was devoted instead to Divination.

Even by Harry's low standards in Divination, the exam went very badly. He might as well have tried to see moving pictures on the desktop as in the stubbornly blank crystal ball; he lost his head completely during tea-leaf reading, saying it looked to him as though Professor Marchbanks would shortly be meeting a round, dark, soggy stranger, and rounded off the whole fiasco by mixing up the life and head lines on her palm and informing her that she ought to have died the previous Tuesday.

'Well, we were always going to fail that one,' said Ron gloomily as they ascended the marble staircase. He had just made Harry feel rather better by telling him how he had told the examiner in detail about the ugly man with a wart on his nose in his crystal ball, only to look up and realise he had been describing his examiner's reflection.

'We shouldn't have taken the stupid subject in the first place,' said Harry.

'Still, at least we can give it up now.'

'Yeah,' said Harry. 'No more pretending we care what happens when Jupiter and Uranus get too friendly.'

'And from now on, I don't care if my tea-leaves spell die, Ron, die — I'm just chucking them in the bin where they belong.'

Harry laughed just as Hermione came running up behind them. He stopped laughing at once, in case it annoyed her.

'Well, I think I've done all right in Arithmancy,' she said, and Harry and Ron both sighed with relief. 'Just time for a quick look over our star-charts before dinner, then . . .'

When they reached the top of the Astronomy Tower at eleven o'clock, they found a perfect night for stargazing, cloudless and still. The grounds were bathed in silvery moonlight and there was a slight chill in the air. Each of them set up his or her telescope and, when Professor Marchbanks gave the word, proceeded to fill in the blank star-chart they had been given.

Professors Marchbanks and Tofty strolled among them, watching as they entered the precise positions of the stars and planets they were observing. All was quiet except for the rustle of parchment, the occasional creak of a telescope as it was adjusted on its stand, and the scribbling of many quills. Half an hour passed, then ar hour; the little squares of reflected gold light flickering on the: ground below started to vanish as lights in the castle windows were extinguished.

As Harry completed the constellation Orion on his chart, however, the front doors of the castle opened directly below the parapet where he was standing, so that light spilled down the stone steps a little way across the lawn. Harry glanced down as he made a slight adjustment to the position of his telescope and saw five or six elongated shadows moving over the brightly lit grass before the doors swung shut and the lawn became a sea of darkness once more.

Harry put his eye back to his telescope and refocused it, now examining Venus. He looked down at his chart to enter the planet there, but something distracted him; pausing with his quill suspended over the parchment, he squinted down into the shadowy grounds and saw half a dozen figures walking over the lawn. If they had not been moving, and the moonlight had not been gilding the tops of their heads, they would have been indistinguishable from the dark ground on which they walked. Even at this distance, Harry had a funny feeling he recognised the walk of the squattest of them, who seemed to be leading the group.

He could not think why Umbridge would be taking a stroll outside after midnight, much less accompanied by five others. Then somebody coughed behind him, and he remembered that he was halfway through an exam. He had quite forgotten Venus's position. Jamming his eye to his telescope, he found it again and was once more about to enter it on his chart when, alert for any odd sound, he heard a distant knock which echoed through the deserted grounds, followed immediately by the muffled barking of a large dog.

He looked up, his heart hammering. There were lights on in Hagrid's windows and the people he had observed crossing the lawn were now silhouetted against them. The door opened and he distinctly saw six sharply defined figures walk over the threshold. The door closed again and there was silence.

Harry felt very uneasy. He glanced around to see whether Ron or Hermione had noticed what he had, but Professor Marchbanks came walking behind him at that moment and, not wanting to look as though he was sneaking looks at anyone else's work, Harry hastily bent over his star-chart and pretended to be adding notes to it while really peering over the top of the parapet towards Hagrid's cabin. Figures were now moving across the cabin windows, temporarily blocking the light.

He could feel Professor Marchbanks's eyes on the back of his neck and pressed his eye again to his telescope, staring up at the moon though he had marked its position an hour ago, but as Professor Marchbanks moved on he heard a roar from the distant cabin that echoed through the darkness right to the top of the Astronomy Tower. Several of the people around Harry ducked out from behind their telescopes and peered instead in the direction of Hagrid's cabin.

Professor Tofty gave another dry little cough.

'Try and concentrate, now, boys and girls,' he said softly.

Most people returned to their telescopes. Harry looked to his left. Hermione was gazing transfixed at Hagrid's cabin.

'Ahem — twenty minutes to go,' said Professor Tofty.

Hermione jumped and returned at once to her star-chart; Harry looked down at his own and noticed that he had mis-labelled Venus as Mars. He bent to correct it.

There was a loud BANG from the grounds. Several people cried 'Ouch!' when they poked themselves in the face with the ends of their telescopes as they hastened to see what was going on below.