‘What the hell did you do that for?’ he cried.

‘I’d had enough,’ his sister replied. ‘Mirror, turn Damien back into a mouse. He’s not fit to be a human.’

‘Sis…’ the mouse that had very briefly been Damien landed on its back, squirmed round, scrabbled for a foothold and was lifted up and dumped unceremoniously into Sis’s cardigan pocket. Her other brother gave her a look of mingled terror and respect and wisely said nothing.

‘Right,’ she said. ‘Now at least I can think straight. I hate mice,’ she added, with a slight shudder. In her pocket something wriggled and squeaked. ‘That’s why I’m glad,’ she went on, ‘that we’ve got a cat.’

The wriggly object in her pocket suddenly became terribly still. She patted it affectionately and turned back to face the screen.

‘Now then,’ she said. ‘Mirror, are you still there?’

The head nodded. It was, she noticed, looking at her oddly; almost as if it had never seen a human turn her brother into a mouse in a fit of pique before. There was something else in its eyes besides surprise, though; she gave it a long, curious look and worked out what the something else was.

Respect.

Ah, she said to herself, now we’re getting somewhere. She took a deep breath and made a conscious effort to relax, letting the fear and tension melt out of her like ice cream through the disintegrated tip of a cone. In charge. In control. Now you can do anything you like.

‘Mirror,’ she said, ‘first I want a million pounds. Next, I want a big house in Malibu and another in Chelsea, and a ski lodge in Switzerland and a Porsche with a personalised number-plate and…’

She froze; someone was coming. Her brother Damien yelped, leapt out of her pocket and scrambled under the table and into the Interface, the incomprehensible lash-up of technology that her other brother Carl had improvised to bring them here. He slid through like a jellied eel through a well-greased letterbox, but unfortunately, being a clumsy boy, he caught the edge of the Interface door with the tip of his tail.

‘Oh no for God’s sake!’ Carl screamed, as the door snapped shut.

‘Quiet!’ Sis whispered furiously.

‘But he’s shut the door!’ Carl wailed. ‘We can’t get back without it. He’s safely back on the other side and we’re stuck here.’

‘What do you mean can’t get…?’ Sis faltered. Regrettably, the words can’t get back weren’t what you’d call ambiguous. ‘You mean, like marooned?’

‘Yes.’

She looked round frantically for another exit; if not out of this crazy scenario, then at least out of the room, before anybody came. Not out of the window; this is a castle, remember, so out of the window would mean a long fall into a stagnant moat, and that’s if she was lucky. Only one door. Nowhere to run and nowhere to hide. Oh…

‘Mirror,’ she said. ‘Hide me, quickly.’

The head looked at her, and in its eyes there was enough raw contempt to keep the book reviews page of the Guardian fully supplied for a year. ‘Bad command or file name,’ it said disdainfully. ‘Please retry.’

‘Mirror!’ she repeated imploringly, but the face vanished abruptly and was replaced by a pattern of slowly revolving geometric shapes, the one that makes your head spin if you watch it for too long. Whimpering, she tugged the curtain away from the wall and slipped behind it, just as the door opened and the wicked queen burst in, with an electric torch in one hand and a heavy Le Creuset frying pan in the other. She surveyed the room slowly and carefully, and sniffed.

‘Mirror,’ she commanded, ‘where is she?’

The geometric shapes vanished and the head came back. ‘She’s hiding behind—’ it began, but got no further; because behind the curtain, Sis had found the power switch and turned it off.

You can’t blame her, of course. You could even say it was really rather resourceful, in the circumstances. And, also in her defence, it’s hardly likely that she knew about the quite terrifying possible consequences of pulling the plug on an antiquated system like this one. After all, not many people do know that the principal drawback of Mirrors 3.1 was the very real risk of crashing the whole thing if you tried to shut it down without going through the proper procedure.

Suddenly, everything vanished.

Which is a rather melodramatic way of saying that there was a major systems malfunction, and all the information stored in the wicked queen’s magic mirror was tumbled out of its drawers on to the floor, painstakingly jumbled up and then shovelled back at random; the kind of complete and systematic random it takes a computer to achieve. That, of course, is going to the other extreme, since it gives the impression that all it’s going to take to get it all sorted out is the intervention of a pasty-faced young man with glasses, a beard and a packet of watchmaker’s screwdrivers, probably called Dave or Chris. Sadly, not so. The difference is that all the little bytes and snippets that live behind the glass of the wicked queen’s mirror aren’t mere electrical impulses and digitised items of data; I am not a number, they could all say, and they’d be absolutely right.

For example — Once upon a time, there was the same little house in the same big wood. And it still had a rose racetrack up one side, and a miniature Wisley seething away out front, and a garishly red front door with a vulgar brass knocker. But this time there’s a note pinned to it, and it says—

Or, while we’re on the subject of pigs: a little way off in the same wood there’s another house; bigger, rather less quaint and unmistakable because of the moat, drawbridge, razor wire entanglements, caltrops, mantraps and signposts reading MINEFIELD and BEWARE OF THE DRAGON that occupy about ninety-five per cent of what should have been a fair-sized front lawn. The house itself shines in the morning light like an American bodyguard’s sunglasses.

The pigs in question are up a scaffolding tower, welding a searchlight bracket to the side of the house. There are three of them; and the smallest, having replaced a 5/8” Stilson wrench in his tool belt, wipes his snout on his foreleg and gazes with satisfaction at his trotter work.

‘Right,’ he says. ‘Just the perimeter fence to wire up, and we’re done.’

The middle pig nods. ‘Trotters crossed, lads,’ he says. ‘We’ve tried straw, sticks, brick, breezeblock, stone, kevlar-reinforced concrete and now molybdenum-steel-faced ceramic armour. If this doesn’t do the trick, we’re going to have serious credibility problems with the insurance company.’

‘It’d help if we knew how he does it,’ mused the biggest pig, pushing up the visor of his welding helmet and unclipping the crocodile clip. ‘I don’t care what the forensic boys say, you’re not going to convince me it’s nothing but sheer lungpower. The last lot was better protected than the basement of the Pentagon, and how long did it take him? Thirty seconds, forty-five at the most, and all that hard work and expensive materials turned into so much second-hand Lego. If that’s an example of what huffing and puffing can do, I reckon Oppenheimer and his mates were wasting their time.’

The middling pig grins; even the ring in his nose sparkles merrily in the early morning sun. ‘He might just be in for a surprise this time,’ he says. ‘On account of the seventy gigawatt interactive force field generator I’ve got hidden in the coal bunker. Just let him so much as sneeze near that and he’ll suddenly find out what’s meant by lethal feedback.’

The smallest pig, who’d been scanning the horizon through an infra-red viewer, scuttles down the scaffolding towards his companions. ‘I hope you’re right,’ he mutters, ‘because here he comes, the bastard. Right, positions, everyone. Desmond, you work the console. Eugene, the remotes. I’ll do all the rest.’