‘So explain.’

Zach, of course, should have known that Lev has his own idea of what constitutes an explanation. And certainly should have guessed when told to set down his mug of tea. After that it’s a matter of seconds for Lev to power up his little game. Zach’s protest is strangled mid-breath by a roar of sound, and he whips his head round but the sound is here, within the tent, within him, a swithering tumult within.

too soon, he’s not ready yet

you levellers have no

Zach raises a hand to his temple, trying to sort out the

more time with him, time to

sort out

why the dogs, they’re not

lunging at our wings till

An angry wasp shrills inside Zach’s skull, seethes and buzzes and shrieks, trapped, ricocheting ever louder as it finds no escape from within. ‘Stop,’ he mutters. He’s going to throw up. He swallows, he closes his eyes, he stumbles to his feet.

‘Sit down!’ Lev orders.

The pressure in his head. He can’t bear

Without a thought for the cold he staggers to the entrance and rips open the zip. Peels back his skin.

It’s not the cold that stops him from vomiting, but the shock.

‘Where are we?’ he gasps, as Lev takes his arm and leads him back inside.

‘The first time’s the worst,’ Lev says. ‘Disorienting.’

‘*Where are we?*’

‘How much maths have they taught you?’ When Zach shakes his head, unable to frame a coherent answer—unable even to recall what they’ve done in the last few lessons—Lev prompts him. ‘What about imaginary numbers?’

‘A classic misnomer,’ Zach says, his distress easing. ‘They’re not really imaginary.’

‘And I’ve already told you, neither is this place.’

Zach has never had any doubts about his intelligence, even as a small boy it was his weapon and armour both. *Dumb monkeys*, he’d spit at them till forced to spit blood. Later on, he learned to guard his mouth as well, so effectively that they never even suspected an insult. But dumb monkeys they’ve stayed, a mantra he repeats to himself the way others pray or swear.

‘Do you think we’re stupid?’ he asks Lev.

‘Who’s *we*? Sapiens or cognoscens?’

Zach is silent for a moment.

‘Both, I suppose,’ he answers, reluctantly. Honestly.

He *knew* he’d see that glint in Lev’s eyes, damn him.

‘A few thousand years of philosophy and pure maths and physics and music ought to do it,’ Lev teases. ‘And some other fields whose names you couldn’t pronounce. That’s why I’m so reluctant to explain. *Show rather than tell*, I believe your writers like to say.’

‘You mentioned imaginary numbers, not me.’

‘As an analogy. You can’t count the square root of -1 in the same way you can count mugs or muggles, but it exists. It’s *real*. In your universe you need imaginary numbers to analyse electrical waves, for example, or in quantum mechanics.’

Zach doesn’t fancy the sound of *your universe*, and says so.

‘Another metaphor.’

‘Metaphors are for literature, not science!’

Lev gestures towards the tent closure, his voice crisp. ‘The ice is out there. It’s real, Zach. Not perhaps the two-cheeseburgers-and-a-coke reality you’ve grown up with, but real nevertheless. A crossing place between universes may be the easiest way for you to picture it.’ A laugh. ‘Or training ground.’

The Pace board in Lev’s lap emits its own form of laugh, a ripple of UV light which no sapiens would be able to see.

‘What else can that thing do?’ Zach asks. And immediately hears the opening notes of the *Adagio* from Mozart’s clarinet concerto. They expand and fill the tent with warm Aegean blue—the colour he thought lost forever—the wonderful watery timbre of an authentic basset clarinet which he’s always longed to own. ‘One day,’ he said, ‘I’ll play it for you on a period instrument.’ Laura smiled. ‘One day, we’ll swim there together,’ she said.

Nine weeks after writing his only clarinet concerto, Mozart was dead.

Bella lifts her head and whines, a high skirling tone which raises the hairs on the nape of Zach’s neck. The blue light fades, and though the tent is battened tight, a seam of cold air slips over his skin as though an unseen door has opened.

‘That’s enough for now,’ Lev says. ‘You’re getting there.’

‘Did you hear it? The clarinet?’

‘Not as such, but it’s irrelevant. What matters is that *you’ve* heard it.’

‘Don’t treat me like an idiot!’

Lev’s grin reminds Zach uncomfortably of his own, when listening to his classmates. ‘If I thought you were an idiot, you wouldn’t be here now.’

‘Yeah, just imagine, I could be cuddled up nice and warm and cosy with someone who thinks I’m a lampshade or a doorknob.’

‘Or an AK-47.’

Lev downs the rest of his tea, then goes to rinse the mug in their washing-up water. Dripping, it dangles from his fingers as he crouches over the bucket, suddenly alert. Bella too raises her head and cocks her ears. Despite his excellent hearing, Zach discerns nothing except the susurrus of snow against the walls of the tent; even the wind has ceased its vicious lashings. Nor are there any untoward shadows which threaten the mellow light from their little stove.

Still, there is something insistent about the near silence, which begins to stretch and stretch and stretch like a balloon, till you become disproportionately anxious that it will pop—*for* it to pop. Just before Zach can no longer hold his breath, Lev snaps his wrist to shake out the excess water and lays the mug upside down near the stove. He turns to Zach.

‘It’s time to leave. I *discouraged* the first lot of them, but they’ll be back.’

‘Are you planning to tell me who they are? And maybe—just maybe, mind you—why?’

‘I could tell you they’re fallen angels. I could tell you they’re winged humans from another universe. I could tell you they’re the incarnation of some madman’s agenda. Or your race’s overweening will to power. Which version do you prefer?’

‘How about the *truth*? Frot it, they’ve slaughtered the dogs!’

‘You’re going to have to learn to make your own truth, Zach. That’s why I’m here.’

Chapter Twenty-Five