Greta’s face appeared again at the top of the crevasse, dark against the sky.

‘Find something?’

‘There are bones down here. A polar-bear cub.’ I didn’t look too closely, but that was all it could be. Definitely not a bird, and no way a seal could have come this far from the sea. ‘The body’s completely decomposed.’

‘Bodies don’t decompose on Utgard.’

‘They must be ancient, then.’ Perhaps that explained the size, some prehistoric creature that had dropped dead thousands of years ago — millions, maybe — and been swallowed by the ice. Preserved perfectly, museum-fresh; only revealed this year when the crevasse split open.

And Hagger had died here. A gruesome coincidence, I insisted, trying to shut up the superstitious voices in my head. Still terrifying.

‘Is that what Martin came for?’ she asked.

I looked around. Only my footprints.

‘Martin never came down here.’ That wasn’t quite accurate. ‘Not when he was alive.’

‘Anything else?’ She jerked her head towards the snowmobiles. ‘It’s a long drive back.’

I left the bones in their icy grave. And this time, I remembered to free the snowmobile tracks from the ice before I started the engine.

Nobody enjoyed dinner that night. Hagger’s death made for a brittle mood. People shuffled food around their plates and didn’t make eye contact. Across the table, Fridge gnawed the meat off a chicken drumstick. I tried not to think about the bones in the crevasse.

Quam got the evening off to a bad start. As soon as the food was served, he stood up and tapped his glass with a fork. He had to wait, awkwardly, while the conversations grudgingly wound down.

‘I want to say a few words — since you’re all here.’ He wiped his mouth with his napkin. ‘Martin Hagger’s death is a tragedy. He was a great scientist, a respected colleague, and a good friend.’

That morning, he’d told me Hagger was a busted flush. Glancing around the table, I didn’t see much evidence of good friends. Most of them looked hostile — or just bored. I couldn’t tell if it was Hagger they didn’t care for, or Quam.

‘The important thing is, we don’t let this get in the way of what we’re all doing. The best tribute to Martin Hagger will be carrying on our valuable science here at Zodiac.’

I think I snorted out loud. Fridge, across the table, gave me a funny look. I could have told him that Quam had forbidden me from carrying on the valuable science that Hagger had been doing — but I refrained.

Quam pulled out a piece of paper. ‘I’d like to read a few words. I’m sure they’ll be familiar to most of you, but I think they capture something. By Captain Robert Scott.’

‘Penguin shagger,’ someone said.

Quam ran the paper between finger and thumb to smooth the crease.

‘“I do not regret this journey. We took risks, we knew we took them.”’ He coughed. It’s fair to say, he wasn’t a natural public speaker.

‘“Things have come out against us, and therefore we have no cause for complaint.”’

‘Easy for you to say,’ muttered a voice behind me. But most of the room had settled into a respectful hush. Even on the Platform — heated, insulated, Internetted and well fed — we knew the line between life and death up there was fragile and transparent as a window pane.

Quam raised his glass. ‘To Martin Hagger. We’ll miss him.’

The rest of us shuffled to our feet and mumbled Hagger’s name. ‘We’ll miss him.’

‘And the grant money he brought in.’

Eastman’s voice cut through the toast, loud and meant to be heard. Quam’s face went bright red.

‘That’s in poor taste.’

‘It’s true, isn’t it?’

‘I won’t dignify—’

‘And it wasn’t just the grant money,’ piled in Fridge. ‘Hagger brought in all kinds of extra funding for you.’

‘If you’re insinuating …’

It was fascinating, watching the scientists tear into their base commander like a pack of wolves. Far more than just professional rivalry. I leaned back and watched the sport. The only person who ignored it completely was Annabel. She sat up, finishing-school straight, dismantling her chicken with small, precise cuts.

‘Let’s cut the bullshit,’ said Eastman. ‘We’re all sad Hagger’s dead. But hands up who actually liked the guy.’

It was obscene to play along — but I put up my hand. I owed Hagger that much. Down the table, I saw Greta’s and Jensen’s arms up too. Kennedy, Ashcliffe the polar-bear hunter and Quam followed suit more slowly, reluctant to get drawn in. Fridge’s and Eastman’s hands stayed down. Annabel kept eating.

Someone killed him. Even after our trip to the crevasse, I only half believed it. But that didn’t mean I trusted these people. Was it really possible? Three of them clearly had enough against Hagger they couldn’t even pretend to have liked him. But then if you’d killed him, you’d probably hide your motive a bit better. Or double-bluff. Or …

If I thought like that, I’d tie myself in knots until I doubted everything. Meanwhile, Quam was still standing. ‘I think an apology’s in order.’

Like a lot of Americans, Eastman had a naturally theatrical presence. He looked around the table and gave a small bow. ‘I’m sorry if I embarrassed your British, uh, sensibilities.’ Heavy with sarcasm. ‘But let’s not pretend this was something it’s not. He’s not a martyr to science. He died; it was an accident. Move on.’

‘If it was an accident,’ I said. I thought nobody heard me.

Eastman checked his watch. ‘Isn’t it time to get the mag reading?’

The others suddenly took a keen interest in their half-empty plates. I was too slow; I caught his eye.

‘Anderson’s the rookie — he should go.’

‘He’s going home tomorrow,’ Quam pointed out.

‘Then this is his only chance.’

I wasn’t going to be haggled over. I stood. ‘What do I have to do?’

‘There’s a logbook in the mag hut. Write down the number on the readout, and the time. Wait ten minutes, do it again. That’s it.’

I was glad to get out, even with all the fiddle of layering up again. I took a gun from the rack by the door — already second nature — and clomped down the steel steps. The cold air pinched my nose dry; my eyes watered. I’d forgotten my neck-warmer, and by the time I was halfway across the base my chin stung as if I had lockjaw. That was the thing with Zodiac. No slack.

I stopped at the flag line, where the ring that surrounded the magnetometer hut met the base perimeter. A sign warned me, NO METAL OBJECTS BEYOND THIS POINT.

I didn’t see anywhere to put the gun. After a moment’s thought, I laid it down on the snow. Strange to say, I felt incomplete without it, like taking off a wedding ring. Walking across the circle of snow to the hut, the immensity of my surroundings pressed in on me. Twilight had fallen; a few stars were bright enough to show in the sky. I checked the shadows for signs of danger, ready to run back for the gun if I saw anything that looked like a bear.

The hut was a simple, one-room wooden cabin, almost colder than the air outside. A wooden table stood in the centre, two grey boxes on top of it like outmoded stereo components. The logbook lay beside them, a battered exercise book with a pencil hanging off it on a piece of string.

I wiped a layer of frost off the readout and studied it. A thin digital line scribbled up and down the screen, recording infinitesimal oscillations in something I couldn’t even imagine. I looked for an obvious number to write down, and didn’t see it.

In the chill quiet, the steps in the snow sounded as loud as bubblegum popping. I looked at the door; I listened. The steps came closer. Two legs, or four?

There was no lock on the hut, and my gun was back at the flag line. Could a polar bear open a door? Could he fit through? I’d thought the bear warnings were just talk, a fairy tale to frighten new arrivals. But human beings are uniquely bad at judging risk. The longer something doesn’t happen, the more confident we become it won’t. We don’t see the sand running out of the glass.