‘I know that you are preparing to fight.’ There were screams amongst the students, some of whom clutched each other, looking around in terror for the source of the sound. ‘Your efforts are futile. You cannot fight me. I do not want to kill you. I have great respect for the teachers of Hogwarts. I do not want to spill magical blood.’

  There was silence in the Hall now, the kind of silence that presses against the eardrums, that seems too huge to be contained by walls.

  ‘Give me Harry Potter,’ said Voldemort’s voice, ‘and none shall be harmed. Give me Harry Potter, and I shall leave the school untouched. Give me Harry Potter, and you will be rewarded.

  ‘You have until midnight.’

  The silence swallowed them all again. Every head turned, every eye in the place seemed to have found Harry, to hold him frozen in the glare of thousands of invisible beams. Then a figure rose from the Slytherin table and he recognised Pansy Parkinson as she raised a shaking arm and screamed, ‘But he’s there! Potter’s there! Someone grab him!’

  Before Harry could speak, there was a massive movement. The Gryffindors in front of him had risen and stood facing, not Harry, but the Slytherins. Then the Hufflepuffs stood, and, almost at the same moment, the Ravenclaws, all of them with their backs to Harry, all of them looking towards Pansy instead, and Harry, awestruck and overwhelmed, saw wands emerging everywhere, pulled from beneath cloaks and from under sleeves.

  ‘Thank you, Miss Parkinson,’ said Professor McGonagall in a clipped voice. ‘You will leave the Hall first with Mr Filch. If the rest of your house could follow.’

  Harry heard the grinding of benches and then the sound of the Slytherins trooping out on the other side of the Hall.

  ‘Ravenclaws, follow on!’ cried Professor McGonagall.

  Slowly, the four tables emptied. The Slytherin table was completely deserted, but a number of older Ravenclaws remained seated while their fellows filed out: even more Hufflepuffs stayed behind, and half of Gryffindor remained in their seats, necessitating Professor McGonagall’s descent from the teachers’ platform to chivvy the under-age on their way.

  ‘Absolutely not, Creevey, go! And you, Peakes!’

  Harry hurried over to the Weasleys, all sitting together at the Gryffindor table.

  ‘Where are Ron and Hermione?’

  ‘Haven’t you found –?’ began Mr Weasley, looking worried.

  But he broke off as Kingsley had stepped forwards on the raised platform to address those who had remained behind.

  ‘We’ve only got half an hour until midnight, so we need to act fast! A battle plan has been agreed between the teachers of Hogwarts and the Order of the Phoenix. Professors Flitwick, Sprout and McGonagall are going to take groups of fighters up to the three highest Towers – Ravenclaw, Astronomy and Gryffindor – where they’ll have a good overview, excellent positions from which to work spells. Meanwhile, Remus,’ he indicated Lupin, ‘Arthur,’ he pointed towards Mr Weasley, sitting at the Gryffindor table, ‘and I will take groups into the grounds. We’ll need somebody to organise defence of the entrances of the passageways into the school –’

  ‘– sounds like a job for us,’ called Fred, indicating himself and George, and Kingsley nodded his approval.

  ‘All right, leaders up here and we’ll divide up the troops!’

  ‘Potter,’ said Professor McGonagall, hurrying up to him, as students flooded the platform, jostling for position, receiving instructions, ‘aren’t you supposed to be looking for something?’

  ‘What? Oh,’ said Harry, ‘oh yeah!’

  He had almost forgotten about the Horcrux, almost forgotten that the battle was being fought so that he could search for it: the inexplicable absence of Ron and Hermione had momentarily driven every other thought from his mind.

  ‘Then go, Potter, go!’

  ‘Right – yeah –’

  He sensed eyes following him as he ran out of the Great Hall again, into the Entrance Hall still crowded with evacuating students. He allowed himself to be swept up the marble staircase with them, but at the top he hurried off along a deserted corridor. Fear and panic were clouding his thought processes. He tried to calm himself, to concentrate on finding the Horcrux, but his thoughts buzzed as frantically and fruitlessly as wasps trapped beneath a glass. Without Ron and Hermione to help him, he could not seem to marshal his ideas. He slowed down, coming to a halt halfway along an empty passage, where he sat down upon the plinth of a departed statue and pulled the Marauder’s Map out of the pouch around his neck. He could not see Ron or Hermione’s names anywhere on it, though the density of the crowd of dots now making its way to the Room of Requirement might, he thought, be concealing them. He put the map away, pressed his hands over his face and closed his eyes, trying to concentrate …

  Voldemort thought I’d go to Ravenclaw Tower.

  There it was: a solid fact, the place to start. Voldemort had stationed Alecto Carrow in the Ravenclaw common room, and there could only be one explanation: Voldemort feared that Harry already knew his Horcrux was connected to that house.

  But the only object anyone seemed to associate with Ravenclaw was the lost diadem … and how could the Horcrux be the diadem? How was it possible that Voldemort, the Slytherin, had found the diadem that had eluded generations of Ravenclaws? Who could have told him where to look, when nobody had seen the diadem in living memory?

  In living memory …

  Beneath his fingers, Harry’s eyes flew open again. He leapt up from the plinth and tore back the way he had come, now in pursuit of his one last hope. The sound of hundreds of people marching towards the Room of Requirement grew louder and louder as he returned to the marble stairs. Prefects were shouting instructions, trying to keep track of the students in their own houses; there was much pushing and shoving; Harry saw Zacharias Smith bowling over first-years to get to the front of the queue; here and there younger students were in tears, while older ones called desperately for friends or siblings …

  Harry caught sight of a pearly-white figure drifting across the Entrance Hall below and yelled as loudly as he could over the clamour.

  ‘Nick! NICK! I need to talk to you!’

  He forced his way back through the tide of students, finally reaching the bottom of the stairs where Nearly Headless Nick, ghost of Gryffindor Tower, stood waiting for him.

  ‘Harry! My dear boy!’

  Nick made to grasp Harry’s hands with both of his own: Harry’s felt as though they had been thrust into icy water.

  ‘Nick, you’ve got to help me. Who’s the ghost of Ravenclaw Tower?’

  Nearly Headless Nick looked surprised, and a little offended.

  ‘The Grey Lady, of course; but if it is ghostly services you require –?’

  ‘It’s got to be her – d’you know where she is?’

  ‘Let’s see …’

  Nick’s head wobbled a little on his ruff as he turned hither and thither, peering over the heads of the swarming students.

  ‘That’s her over there, Harry, the young woman with the long hair.’

  Harry looked in the direction of Nick’s transparent, pointing finger and saw a tall ghost who caught sight of Harry looking at her, raised her eyebrows, and drifted away through a solid wall.

  Harry ran after her. Once through the door of the corridor into which she had disappeared, he saw her at the very end of the passage, still gliding smoothly away from him.

  ‘Hey – wait – come back!’

  She consented to pause, floating a few inches from the ground. Harry supposed that she was beautiful, with her waist-length hair and floor-length cloak, but she also looked haughty and proud. Close to, he recognised her as a ghost he had passed several times in the corridor, but to whom he had never spoken.

  ‘You’re the Grey Lady?’

  She nodded but did not speak.

  ‘The ghost of Ravenclaw Tower?’

  ‘That is correct.’

  Her tone was not encouraging.

  ‘Please: I need some help. I need to know anything you can tell me about the lost diadem.’

  A cold smile curved her lips.

  ‘I am afraid,’ she said, turning to leave, ‘that I cannot help you.’

  ‘WAIT!’

  He had not meant to shout, but anger and panic were threatening to overwhelm him. He glanced at his watch as she hovered in front of him: it was a quarter to midnight.

  ‘This is urgent,’ he said fiercely. ‘If that diadem’s at Hogwarts, I’ve got to find it, fast.’

  ‘You are hardly the first student to covet the diadem,’ she said disdainfully. ‘Generations of students have badgered me –’

  ‘This isn’t about trying to get better marks!’ Harry shouted at her. ‘It’s about Voldemort – defeating Voldemort – or aren’t you interested in that?’

  She could not blush, but her transparent cheeks became more opaque, and her voice was heated as she replied, ‘Of course I – how dare you suggest –?’

  ‘Well, help me, then!’

  Her composure was slipping.

  ‘It – it is not a question of –’ she stammered. ‘My mother’s diadem –’

  ‘Your mother’s?’

  She looked angry with herself.

  ‘When I lived,’ she said stiffly, ‘I was Helena Ravenclaw.’

  ‘You’re her daughter? But then, you must know what happened to it!’

  ‘While the diadem bestows wisdom,’ she said, with an obvious effort to pull herself together, ‘I doubt that it would greatly increase your chances of defeating the wizard who calls himself Lord –’

  ‘Haven’t I just told you, I’m not interested in wearing it!’ Harry said fiercely. ‘There’s no time to explain – but if you care about Hogwarts, if you want to see Voldemort finished, you’ve got to tell me anything you know about the diadem!’

  She remained quite still, floating in mid-air, staring down at him, and a sense of hopelessness engulfed Harry. Of course, if she had known anything, she would have told Flitwick or Dumbledore, who had surely asked her the same question. He had shaken his head, and made to turn away, when she spoke in a low voice.

  ‘I stole the diadem from my mother.’

  ‘You – you did what?’

  ‘I stole the diadem,’ repeated Helena Ravenclaw in a whisper. ‘I sought to make myself cleverer, more important than my mother. I ran away with it.’

  He did not know how he had managed to gain her confidence, and did not ask: he simply listened, hard, as she went on, ‘My mother, they say, never admitted that the diadem was gone, but pretended that she had it still. She concealed her loss, my dreadful betrayal, even from the other founders of Hogwarts.

  ‘Then my mother fell ill – fatally ill. In spite of my perfidy, she was desperate to see me one more time. She sent a man who had long loved me, though I spurned his advances, to find me. She knew that he would not rest until he had done so.’

  Harry waited. She drew a deep breath and threw back her head.

  ‘He tracked me to the forest where I was hiding. When I refused to return with him, he became violent. The Baron was always a hot-tempered man. Furious at my refusal, jealous of my freedom, he stabbed me.’

  ‘The Baron? You mean –?’

  ‘The Bloody Baron, yes,’ said the Grey Lady, and she lifted aside the cloak she wore to reveal a single dark wound in her white chest. ‘When he saw what he had done, he was overcome with remorse. He took the weapon that had claimed my life, and used it to kill himself. All these centuries later, he wears his chains as an act of penitence … as he should,’ she added bitterly.

  ‘And … and the diadem?’

  ‘It remained where I had hidden it when I heard the Baron blundering through the forest towards me. Concealed inside a hollow tree.’

  ‘A hollow tree?’ repeated Harry. ‘What tree? Where was this?’

  ‘A forest in Albania. A lonely place I thought was far beyond my mother’s reach.’

  ‘Albania,’ repeated Harry. Sense was emerging miraculously from confusion, and now he understood why she was telling him what she had denied Dumbledore and Flitwick. ‘You’ve already told someone this story, haven’t you? Another student?’

  She closed her eyes and nodded.

  ‘I had … no idea … he was … flattering. He seemed to … to understand … to sympathise …’

  Yes, Harry thought, Tom Riddle would certainly have understood Helena Ravenclaw’s desire to possess fabulous objects to which she had little right.

  ‘Well, you weren’t the first person Riddle wormed things out of,’ Harry muttered. ‘He could be charming when he wanted …’

  So Voldemort had managed to wheedle the location of the lost diadem out of the Grey Lady. He had travelled to that far-flung forest and retrieved the diadem from its hiding place, perhaps as soon as he left Hogwarts, before he even started work at Borgin and Burkes.

  And wouldn’t those secluded Albanian woods have seemed an excellent refuge when, so much later, Voldemort had needed a place to lie low, undisturbed, for ten long years?

  But the diadem, once it became his precious Horcrux, had not been left in that lowly tree … no, the diadem had been returned secretly to its true home, and Voldemort must have put it there –

  ‘– the night he asked for a job!’ said Harry, finishing his thought.

  ‘I beg your pardon?’

  ‘He hid the diadem in the castle, the night he asked Dumbledore to let him teach!’ said Harry. Saying it out loud enabled him to make sense of it all. ‘He must’ve hidden the diadem on his way up to, or down from, Dumbledore’s office! But it was still worth trying to get the job – then he might’ve got the chance to nick Gryffindor’s sword as well – thank you, thanks!’

  Harry left her floating there, looking utterly bewildered. As he rounded the corner back into the Entrance Hall, he checked his watch. It was five minutes until midnight, and though he now knew what the last Horcrux was, he was no closer to discovering where it was …

  Generations of students had failed to find the diadem; that suggested that it was not in the Ravenclaw Tower – but if not there, where? What hiding place had Tom Riddle discovered inside Hogwarts Castle, that he believed would remain secret forever?

  Lost in desperate speculation, Harry turned a corner, but he had taken only a few steps down the new corridor when the window to his left broke open with a deafening, shattering crash. As he leapt aside, a gigantic body flew in through the window and hit the opposite wall. Something large and furry detached itself, whimpering, from the new arrival and flung itself at Harry.

  ‘Hagrid!’ Harry bellowed, fighting off Fang the boarhound’s attentions as the enormous bearded figure clambered to his feet. ‘What the –?’

  ‘Harry, yer here! Yer here!’

  Hagrid stooped down, bestowed upon Harry a cursory and rib-cracking hug, then ran back to the shattered window.

  ‘Good boy, Grawpy!’ he bellowed through the hole in the window. ‘I’ll see yer in a moment, there’s a good lad!’

  Beyond Hagrid, out in the dark night, Harry saw bursts of light in the distance and heard a weird, keening scream. He looked down at his watch: it was midnight. The battle had begun.

  ‘Blimey, Harry,’ panted Hagrid, ‘this is it, eh? Time ter fight?’

  ‘Hagrid, where have you come from?’

  ‘Heard You-Know-Who from up in our cave,’ said Hagrid grimly. ‘Voice carried, didn’ it? “Yeh got ’til midnight ter gimme Potter.” Knew yeh mus’ be here, knew what mus’ be happenin’. Get down, Fang. So we come ter join in, me an’ Grawpy an’ Fang. Smashed our way through the boundary by the forest, Grawpy was carryin’ us, Fang an’ me. Told him ter let me down at the castle so he shoved me through the window, bless him. Not exac’ly what I meant, bu’ – where’s Ron an’ Hermione?’

  ‘That,’ said Harry, ‘is a really good question. Come on.’

  They hurried together along the corridor, Fang lolloping beside them. Harry could hear movement through the corridors all around: running footsteps, shouts; through the windows, he could see more flashes of light in the dark grounds.

  ‘Where’re we goin’?’ puffed Hagrid, pounding along at Harry’s heels, making the floorboards quake.

  ‘I dunno exactly,’ said Harry, making another random turn, ‘but Ron and Hermione must be around here somewhere.’

  The first casualties of the battle were already strewn across the passage ahead: the two stone gargoyles that usually guarded the entrance to the staff room had been smashed apart by a jinx that had sailed through another broken window. Their remains stirred feebly on the floor, and as Harry leapt over one of their disembodied heads it moaned faintly, ‘Oh, don’t mind me … I’ll just lie here and crumble …’

  Its ugly stone face made Harry think suddenly of the marble bust of Rowena Ravenclaw at Xenophilius’s house, wearing that mad headdress – and then of the statue in Ravenclaw Tower, with the stone diadem upon her white curls …

  And as he reached the end of the passage, the memory of a third stone effigy came back to him: that of an ugly old warlock, on to whose head Harry himself had placed a wig and a battered, old tiara. The shock shot through Harry with the heat of Firewhisky, and he nearly stumbled.

  He knew, at last, where the Horcrux sat waiting for him …

  Tom Riddle, who confided in no one and operated alone, might have been arrogant enough to assume that he, and only he, had penetrated the deepest mysteries of Hogwarts Castle. Of course, Dumbledore and Flitwick, those model pupils, had never set foot in that particular place, but he, Harry, had strayed off the beaten track in his time at school – here at last was a secret he and Voldemort knew, that Dumbledore had never discovered –

  He was roused by Professor Sprout, who was thundering past followed by Neville and half a dozen others, all of them wearing earmuffs and carrying what appeared to be large potted plants.

  ‘Mandrakes!’ Neville bellowed at Harry over his shoulder as he ran. ‘Going to lob them over the walls – they won’t like this!’

  Harry knew, now, where to go: he sped off, with Hagrid and Fang galloping behind him. They passed portrait after portrait, and the painted figures raced alongside them, wizards and witches in ruffs and breeches, in armour and cloaks, cramming themselves into each other’s canvases, screaming news from other parts of the castle. As they reached the end of this corridor, the whole castle shook and Harry knew, as a gigantic vase blew off its plinth with explosive force, that it was in the grip of enchantments more sinister than those of the teachers and the Order.