'Right-o,' Fred said brightly, spraying the Doxy quickly in the face so that it fainted, but the moment Mrs Weasley's back was turned he pocketed it with a wink.

'We want to experiment with Doxy venom for our Skiving Snackboxes,' George told Harry under his breath.

Deftly spraying two Doxys at once as they soared straight for his nose, Harry moved closer to George and muttered out of the corner of his mouth, 'What are Skiving Snackboxes?'

'Range of sweets to make you ill,' George whispered, keeping a wary eye on Mrs Weasley's back. 'Not seriously ill, mind, just ill enough to get you out of a class when you feel like it. Fred and I have been developing them this summer. They're double-ended, colour-coded chews. If you eat the orange half of the Puking Pastilles, you throw up. Moment you've been rushed out of the lesson for the hospital wing, you swallow the purple half — '

' — which restores you to full fitness, enabling you to pursue the leisure activity of your own choice during an hour that would otherwise have been devoted to unprofitable boredom." That's what we're putting in the adverts, anyway,' whispered Fred, who had edged over out of Mrs Weasley's line of vision and was now sweeping a few stray Doxys from the floor and adding them to his pocket. 'But they still need a bit of work. At the moment our testers are having a bit of trouble stopping themselves puking long enough to swallow the purple end.'

'Testers?'

'Us,' said Fred. 'We take it in turns. George did the Fainting Fancies — we both tried the Nosebleed Nougat — '

'Mum thought we'd been duelling,' said George.

'Joke shop still on, then?' Harry muttered, pretending to be adjusting the nozzle on his spray.

'Well, we haven't had a chance to get premises yet,' said Fred, dropping his voice even lower as Mrs Weasley mopped her brow with her scarf before returning to the attack, 'so we're running it as a mail-order service at the moment. We put advertisements in the Daily Prophet last week.'

'All thanks to you, mate,' said George. 'But don't worry . . . Mum hasn't got a clue. She won't read the Daily Prophet any more, 'cause of it telling lies about you and Dumbledore.'

Harry grinned. He had forced the Weasley twins to take the thousand Galleons prize money he had won in the Triwizard Tournament to help them realise their ambition to open a joke shop, but he was still glad to know that his part in furthering their plans was unknown to Mrs Weasley. She did not think running a joke shop was a suitable career for two of her sons.

The de-Doxying of the curtains took most of the morning. It was past midday when Mrs Weasley finally removed her protective scarf, sank into a sagging armchair and sprang up again with a cry of disgust, having sat on the bag of dead rats. The curtains were no longer buzzing; they hung limp and damp from the intensive spraying. At the foot of them unconscious Doxys lay crammed in the bucket beside a bowl of their black eggs, at which Crookshanks was now sniffing and Fred and George were shooting covetous looks.

'I think we'll tackle those after lunch.' Mrs Weasley pointed at the dusty glass-fronted cabinets standing on either side of the mantelpiece. They were crammed with an odd assortment of objects: a selection of rusty daggers, claws, a coiled snakeskin, a number of tarnished silver boxes inscribed with languages Harry could lot understand and, least pleasant of all, an ornate crystal bottle with a large opal set into the stopper, full of what Harry was quite sure was blood.

The clanging doorbell rang again. Everyone looked at Mrs Weasley.

'Stay here,' she said firmly, snatching up the bag of rats as Mrs Blacks screeches started up again from down below. 'I'll bring up some sandwiches.'

She left the room, closing the door carefully behind her. At once, everyone dashed over to the window to look down on the doorstep. They could see the top of an unkempt gingery head and a suck of precariously balanced cauldrons.

'Mundungus!' said Hermione. 'What's he brought all those cauldrons for?'

'Probably looking for a safe place to keep them,' said Harry. 'Isn't that what he was doing the night he was supposed to be tailing me? Picking up dodgy cauldrons?'

'Yeah, you're right!' said Fred, as the front door opened; Mundungus heaved his cauldrons through it and disappeared from view. 'Blimey, Mum won't like that . . .'

He and George crossed to the door and stood beside it, listening closely. Mrs Black's screaming had stopped.

'Mundungus is talking to Sirius and Kingsley,' Fred muttered, frowning with concentration. 'Can't hear properly . . . d'you reckon we can risk the Extendable Ears?'

'Might be worth it,' said George. 'I could sneak upstairs and get a pair — '

But at that precise moment there was an explosion of sound from downstairs that rendered Extendable Ears quite unnecessary. All of them could hear exactly what Mrs Weasley was shouting at the top of her voice.

'WE ARE NOT RUNNING A HIDEOUT FOR STOLEN GOODS!'

'I love hearing Mum shouting at someone else,' said Fred, with a satisfied smile on his face as he opened the door an inch or so to allow Mrs Weasley's voice to permeate the room better, 'it makes such a nice change.'

' — COMPLETELY IRRESPONSIBLE, AS IF WE HAVEN'T GOT ENOUGH TO WORRY ABOUT WITHOUT YOU DRAGGING STOLEN CAULDRONS INTO THE HOUSE — '

'The idiots are letting her get into her stride,' said George, shaking his head. 'You've got to head her off early otherwise she builds up a head of steam and goes on for hours. And she's been dying to have a go at Mundungus ever since he sneaked off when he was supposed to be following you, Harry — and there goes Sirius's mum again.'

Mrs Weasley's voice was lost amid fresh shrieks and screams from the portraits in the hall.

George made to shut the door to drown the noise, but before he could do so, a house-elf edged into the room.

Except for the filthy rag tied like a loincloth around its middle, it was completely naked. It looked very old. Its skin seemed to be several times too big for it and, though it was bald like all house-elves, there was a quantity of white hair growing out of its large, batlike ears. Its eyes were a bloodshot and watery grey and its fleshy nose was large and rather snoutlike.

The elf took absolutely no notice of Harry and the rest. Acting as though it could not see them, it shuffled hunchbacked, slowly and doggedly, towards the far end of the room, all the while muttering under its breath in a hoarse, deep voice like a bullfrog's.

'. . . smells like a drain and a criminal to boot, but she's no better, nasty old blood traitor with her brats messing up my mistress's house, oh, my poor mistress, if she knew, if she knew the scum they've let into her house, what would she say to old Kreacher, oh, the shame of it, Mudbloods and werewolves and traitors and thieves, poor old Kreacher, what can he do . . .'

'Hello, Kreacher,' said Fred very loudly, closing the door with a snap.

The house-elf froze in his tracks, stopped muttering, and gave a very pronounced and very unconvincing start of surprise.

'Kreacher did not see young master,' he said, turning around and bowing to Fred. Still lacing the carpet, he added, perfectly audibly, 'Nasty little brat of a blood traitor it is.'

'Sorry?' said George. 'Didn't catch that last bit.'

'Kreacher said nothing,' said the elf, with a second box to George, adding in a clear undertone, 'and there its twin, unnataral little beasts they are.'

Harry didn't know whether to laugh or not. The elf straightened up, eyeing them all malevolently, and apparently convinced that they could not hear him as he continued to mutter.

'. . . and there's the Mudblood, standing there bold as brass, oh if my mistress knew, oh, how she'd cry, and there's a new boy, Kreacher doesn't know his name. What is he doing here? Kreacher doesn't know . . .'

'This is Harry, Kreacher,' said Hermione tentatively. 'Harry Potter.'

Kreacher's pale eyes widened and he muttered faster and more furiously than ever.

'The Mudblood is talking to Kreacher as though she is my friend, if Kreacher's mistress saw him in such company, oh, what would she say — '

'Don't call her a Mudblood!' said Ron and Ginny together, very angrily.

'It doesn't matter,' Hermione whispered, 'he's not in his tight mind, he doesn't know what he's — '

'Don't kid yourself, Hermione, he knows exactly what he's saying,' said Fred, eyeing Kreacher with great dislike.

Kreacher was still muttering, his eyes on Harry.

'Is it true? Is it Harry Potter? Kreacher can see the scar, it must be true, that's the boy who stopped the Dark Lord, Kreacher wonders how he did it — '

'Don't we all, Kreacher,' said Fred.

'What do you want, anyway?' George asked.

Kreacher's huge eyes darted towards George.

'Kreacher is cleaning,' he said evasively.

'A likely story,' said a voice behind Harry.

Sirius had come back; he was glowering at the elf from the doorway. The noise in the hall had abated; perhaps Mrs Weasley and Mundungus had moved their argument down into the kitchen.

At the sight of Sirius, Kreacher flung himself into a ridiculously low bow that flattened his snoutlike nose on the floor.

'Stand up straight,' said Sirius impatiently. 'Now, what are you up to?'

'Kreacher is cleaning,' the elf repeated. 'Kreacher lives to serve the Noble House of Black — '

'And it's getting blacker every day, it's filthy,' said Sirius.

'Master always liked his little joke,' said Kreacher, bowing again, and continuing in an undertone, 'Master was a nasty ungrateful swine who broke his mother's heart — '

'My mother didn't have a heart, Kreacher,' snapped Sirius. 'She kept herself alive out of pure spite.'

Kreacher bowed again as he spoke.

'Whatever Master says,' he muttered furiously. 'Master is not fit to wipe slime from his mother's boots, oh, my poor mistress, what would she say if she saw Kreacher serving him, how she hated him, what a disappointment he was — '

'I asked you what you were up to,' said Sirius coldly. 'Every time you show up pretending to be cleaning, you sneak something off to your room so we can't throw it out.'

'Kreacher would never move anything from its proper place in Master's house,' said the elf, then muttered very fast, 'Mistress would never forgive Kreacher if the tapestry was thrown out, seven centuries it's been in the family, Kreacher must save it, Kreacher will not let Master and the blood traitors and the brats destroy it — '

'I thought it might be that,' said Sirius, casting a disdainful look at the opposite wall. 'She'll have put another Permanent Sticking Charm on the back of it, I don't doubt, but if I can get rid of it I certainly will. Now go away, Kreacher.'