‘Get in.’

I slid in the gap between the snow and the board. Pierre wriggled in beside me — there was just enough room for both of us. He reached up and slid the board back until it completely covered the top of the hole.

‘You see?’

It was breathtaking. Sunlight shone through the thin wall that divided the two pits and lit up the snow, making it glow a perfect holy blue, like a Chagall window. Like the crevasse, only more concentrated in the tiny space. The different snow layers made stripes of light: pale powder blue where it hadn’t compacted, vivid neon where it had.

‘It’s a time machine,’ said Pierre. ‘The darker bands are summer snowfall. The lighter ones are winter. Wind blows more air into them so they’re less dense.’

I sat there and traced the layers, winter and summer, year after year. I counted back: the summer Luke was born; my winter wedding with Louise; the September I started my PhD. I’d gone back as far as the summer I finished primary school before the layers got too thin for me to tell them apart. My life didn’t feel like much compared with the vastness of the snow quietly piling up here.

A rap on the wooden board told me someone else wanted to admire the view. We lifted it up and scrambled out of the hole, being careful not to touch the thin wall. The sun outside dazzled me; I fumbled with my sunglasses before I went blind. The wind cut through my jumper like a razor.

I put on my coat and went to join the others. They were taking a break over by a folding table. Pierre snapped me off a piece of chocolate and gave me a hot cup of tea. It went stone cold in the time I took to drink it.

‘At fifty below, you can throw boiling water in the air and it freezes before it lands,’ said one of the students.

‘We should try it,’ said Pierre. ‘It’s supposed to get cold by the weekend. Big storm coming in.’

‘Send me a link to the video,’ I said. ‘I’ll be gone by then.’

Hard to imagine I’d be watching Dr Who with Luke in the living room. I looked over at our snow pit and thought of the light inside, the blue cathedral of the crevasse. I’d miss that. Other things, not so much.

There’d been a snow pit where Hagger died, I remembered. Except—

The idea hit me so hard I started to tremble. I grabbed Pierre’s arm.

‘Is that how you always dig snow pits? One covered, one open?’

‘Pretty much. Why?’

Some of the others had started to drift back to work. I ran to the coring rig and found Annabel. ‘The place where Hagger died — the Helbreen. How far is it from here?’

‘About thirty kilometres.’

‘I need to go there. Now.’

‘You don’t know the way.’

I could see she didn’t think I was serious. I ran over to a snowmobile and yanked on the starter cord. It was harder than it looked.

‘What the hell do you think you’re doing?’

‘I’m going to the Helbreen.’

‘You’ll kill yourself.’

‘Then you’d better come with me.’ Or else … ‘You don’t want someone else going off there without a buddy.’

The glacier was exactly as we’d left it: the jerrycans marking out the safe area, the yawning blue crevasse beyond. And the snow pit, half filled now with drifting snow. I jumped in and kicked against the walls. One stubbed my toe, so did the next, but the third disintegrated in a blizzard of collapsing snow. A ceiling appeared, a wooden board that had been covered by the drifts, making a small square cave. A red backpack lay on the ground.

I pulled off my mittens and unzipped the bag. There wasn’t much inside: a bar of chocolate, a Thermos (frozen solid), a topographic map, a pen and a green notebook.

I opened the notebook. My hands were already going numb — the thin liners were no match for the icy wind — but this was too important. I turned the pages, searching for any clue to what Hagger had been doing.

It looked like any other lab notebook. Neat columns of figures, measurements, interspersed with scrawled calculations and cryptic half-sentences. Sulphite calibration (double underlined); Ratkowsky growth rate profile; Concentration of X. Without careful reading, I couldn’t guess what it all meant. I could barely read the handwriting.

‘I need a wee,’ said Annabel. She went off behind a pile of moraine boulders at the edge of the glacier. I turned my back and kept reading.

A loose sheet of paper stuck out between the pages. I pulled it out and smoothed it against the notebook’s cover. It was a printout. Easier to read, but that was no help understanding it. Just a string of numbers, no spaces, zeros and ones and twos in an apparently random order: 1100121101012 … Some sort of data set, I supposed.

A gust of wind lifted the paper. I snatched for it, but my fingers were clumsy with cold. It blew out of the notebook and fluttered across the glacier, white against white. In a split second, I could hardly see it.

I wasn’t going to lose it before I knew what it meant. I scrambled out of the pit and ran after it, floundering through the snow, skidding where the wind had scoured out patches of ice. Behind me, Annabel was shouting something, but with my hood up and the wind roaring around me, I didn’t make out the words.

The paper blew up against a rocky outcrop and stopped. I grabbed it, but my fingers wouldn’t move. I clapped it between my hands to lift it, then just about managed to stuff it into my coat pocket. I had to get my mittens back on.

Annabel was still shouting. I looked around to see what she wanted, and realised how far I’d come. Well beyond the safe area. Perhaps that’s what she was trying to tell me.

‘I’m coming,’ I called, and stepped forward.

Something cracked. The ground gave way under me. I felt a sickening emptiness as I fell. I remember thinking, This is how a snowflake feels.

Snow lands soft as a feather. I didn’t. I hit my head, and the white world went black.

The vibrating pager skittered across the tabletop like a beetle. The captain’s hand trapped it right before it went over the edge. He read the screen and stood.

‘Give me a minute.’

Anderson, half buried under the pink blanket, gave a lean smile. ‘I just reached the most exciting part.’

‘Yeah. But the helicopter’s coming in.’

The smile vanished. ‘Any survivors?’

‘That’s what I’m going to find out.’

Franklin closed the door behind him. Santiago was waiting in the corridor.

‘You get anything, boss?’

‘Long story. What’s the word from the boarding party?’

‘ETA five minutes. They said to have a couple of stretchers ready. And to open up the cold locker.’

They climbed the stairs towards the wheelhouse. There were ten decks on the Terra Nova, and wherever you happened to be, the chances were that what you wanted would be on a different deck. A floating StairMaster. The crew were the fittest in the Coast Guard.

Santiago’s voice dropped. ‘We’ve been doing some checking up on this guy. There’s a few wrinkles.’

‘Like?’ They went past the wipe board where the science schedule was written up. Sailing in the Arctic, things changed so often the geeks called it the Board of Lies.

‘For starters, he doesn’t have a PhD like he claimed. He got kicked out of school before he finished — some big scandal. An experiment went wrong, he’d faked the paperwork, they cut him loose.’

‘You figure all that out yourself, Ops?’

Santiago grinned. ‘I got one of the geeks to help me out.’

They came out on the bridge. Franklin crossed to the rear windows and looked down on the flight deck. Snow was blowing over the side, covering the deck as quickly as the crew could sweep it back. He scanned for the helicopter. Couldn’t even find the sky.

‘There, sir.’

Santiago pointed. A dim light had appeared, blinking in the fog like a distant lighthouse. It grew brighter. Rotor blades chopped a hole in the fog.