I don’t know if anyone has ever told you anything so amazing, so literally incredible, that you just cannot believe it – yet at the same time, you have no choice but to believe it?

I guess not, but that’s what it’s like listening to Hellyann in the shadowy bike shop that smells of rubber and oil combined with the pungent odour of alien being blown towards us by the fan heater whenever she walks in front of it.

She paces around, never sitting – a hairy bundle of nervous energy. And for once, Iggy ends up stunned into silence. He sits, unblinking, mouth open.

‘I know where your sister is,’ Hellyann begins.

I nod slowly, my eyes wide and my heart hammering with hope in my chest.

‘She is alife, but she is a long, long way away.’

I lick my dry lips, swallow hard and glance over at Iggy, who hasn’t moved.

‘Look at this.’

She reaches behind her back and detaches the strange, shiny backpack that we saw before when she healed Iggy’s leg. She opens the top and takes out a small, grey, rectangular block about the size of a paperback book, which she positions on the glass-topped table between us.

She strokes her fingers over one end of the book and about 30 centimetres above it appears a bright white line, like a length of super-illuminated floating wire. That impresses me, and I say ‘Woah!’, but Iggy remains silent, as if he knows something even more incredible is about to happen.

From out of the glowing line, a picture appears, blurred at first, then, after a few seconds, slowly becoming pin-sharp. Only, it’s not a picture, it’s a scene, in 3D – like a hologram, only in black and white, like an old movie.

In the scene people are moving around, only a few centimetres tall, on the tabletop in front of us. It looks like a street scene in a city: there are cars, and buildings. Someone throws a ball for a dog; a tree’s branches wave in the wind.

I watch transfixed and I glance across at Iggy, whose eyes are darting from point to point in the scene before us.

‘Why …’ Iggy says, but Hellyann holds up her hand to stop him.

She reaches into the scene, her hands passing through the seemingly solid people and buildings, and strokes the ‘book’ again, making the picture freeze. The scene changes, and a grid appears, dividing the scene into dozens of little blocks, then one of the blocks grows to fill the space.

And there she is.

Slowly, I reach forward, my hand trembling, lips parted. There’s no mistaking who it is.

I say, ‘Tammy …’

The picture moves again. Tammy’s 3D head is almost life-size and the detail is incredible, even if the image is not in colour. She turns, but she’s not looking at us; her eyes are blank and her face displays an empty half-smile. She touches her chest with her hand and says, ‘Tammy.’ Then an off-camera voice says, ‘Hellyann.’

I’m breathing heavily and, to my surprise, tears are streaming down my face although I didn’t know I was crying.

‘What … I mean … where? Where is she?’ I say quietly.

‘She is in danger,’ says Hellyann. ‘Very grafe danger.’

The image on the glass tabletop fades and dies.

Iggy lifts his face to stare at Hellyann. ‘Did you … kidnap her?’

‘Not me.’ She says it so quickly and forcefully that I immediately believe her. ‘But yes, she was taken. She was taken py someone who then solt her.’

‘Sold her? Who to? What for? Is she OK?’

My mind is racing with the horrible possibilities.

Hellyann speaks slowly, as though she’s trying to be gentle. She kneels down in front of us.

‘Nothing ferry bad has happent to her. Not yet. She is not even aware of her situation, thanks to a process that you would call “consciousness-erasing” or “mind-cleaning”.’

‘Like a computer memory wipe?’ I suggest fearfully, and Hellyann nods.

‘Yes. But to not worry about that: her consciousness is simply masked. Hidden, you might say. And we can, I pelieve, get her pack.’

There’s a long pause.

Eventually, I say, ‘We?’

Hellyann stands up. ‘Yes,’ she says. ‘We. This is dangerous. I neet your help. I cannot to this alone.’

I’ve had enough. I want to be told the whole truth, right now, and I throw out my arms in frustration. ‘Where is she?’ I demand with my voice rising and stamping my foot with each word.

Hellyann seems unmoved and carries on speaking in her guttural monotone.

‘Have a look at this,’ she says. She strokes the silver-grey block and the picture appears again: the street scene with tiny figures moving about, and the hum of a city street. ‘This looks like Earth, yes?’

We look carefully. The buildings, the cars, the trees, the dog …

‘Yeah,’ I say. ‘I suppose … wow!’

I stop when a huge pair of birds, like hawks or ospreys, swoops into the scene, circles, and flies out.

Hellyann enlarges the scene again to show a shopfront, only it looks like a shopfront from years ago – an old village toyshop, like you see in pictures.

The more we look, the odder it becomes. The cars on the street are a strange mixture of styles: a low sports car, and an ancient, rattling wagon from, I don’t know, the 1920s or something. There’s even a tractor.

And the people – there are maybe ten or twenty of them, no more. The same people walk up and down the street, in and out of the shops, crossing the road pointlessly again and again. A woman gets in her car, drives it up the street and out of the scene, and then it reappears coming the other way, after which she parks it, gets out, goes into a shop and then does the whole thing again.

Iggy and I watch, transfixed, literally speechless.

Then Iggy utters a groan. ‘Oh my God! Look!’

Two figures appear. Creatures, just like Hellyann: naked, pale and hairy, with tails. They walk down the middle of the street, looking about them and pointing.

‘It’s all fake,’ I say, but Iggy shakes his head.

‘It’s not fake,’ he whispers. ‘It’s real. It’s … it’s a zoo!’

I feel sick and turn away, directing my anger at Hellyann.

‘That’s horrible! Why would you do that?’

Hellyann has picked up Suzy and is holding her gently. She blinks and looks back at me with her strange, wide-eyed gaze. ‘For knowletch. For learning. But I akree it is wrong. That is why I am here.’

Iggy and I glance at each other, dumbfounded, and Hellyann continues to stroke Suzy. ‘I haf neffer held an animal before,’ she says. ‘It feels goot!’