We loaded the last box. Jensen still had some refuelling to do; Fridge and I retreated out of range of the propellers, watching Annabel’s team take ice cores. Like most science, it involved a lot of waiting. A steel cable spun lazily from a tripod. Somewhere on the end of it, deep inside the ice, it turned a hollow drill bit, cutting out the glacier like coring an apple. I kept expecting something to come out, but it never did.

Fridge cleared his throat. ‘Last night. Eastman’s game. It was wrong I didn’t put my hand up. Martin deserved better.’

I made a no-hard-feelings gesture. ‘I heard you were friends.’

‘From way back. We both were at McMurdo in the eighties. In the south.’

Almost everywhere on the planet is south of Utgard. It took me a moment to work out that he meant Antarctica.

‘So what happened here?’

‘It was dumb. We disagreed over an interpretation of the data.’

‘Data?’

‘We detected high methane levels in the first-year sea ice. I thought it was atmospheric; Martin thought it had a bio-logical origin.’ He saw the look on my face and cracked a rueful smile. ‘Stupid, right?’

I didn’t comment. Fridge stared out at the white plateau around us. ‘This place — you think it’s going to be perfect space. Mind-expanding. But actually, it just boxes you in.’

He broke off as Jensen came over from the helicopter. ‘Ready to go?’

‘Problem with the weight,’ said Jensen. ‘Annabel drilled too much bloody ice. I’ve only got room for one.’

‘I’ll stay,’ I volunteered.

I watched the helicopter lift off, whipping up the snow as if someone had shaken a snow globe. When it had disappeared behind the mountains, I wandered over to the drill rig.

‘Anything I can do?’

Annabel looked round. ‘How much do you know about glaciers?’

‘I’m a fast learner.’

‘Then let me give you Glaciology 101. Glaciers are ice, but they’re made of snow. Snow falls, and because it’s so cold here it doesn’t melt. As it piles up, year after year, the weight of the new snow above compresses the old snow and changes its crystal structure to ice. Each year, another layer forms.’

‘OK.’

‘Now, the important thing about glaciers is that although they’re frozen, they don’t stand still. They’re fluid. The ice is actually flowing very slowly, moving outwards under its own weight.’

I looked at my feet. The ground seemed solid enough.

‘Imagine pressing down on a balloon. The more pressure you apply on top, the wider it spreads out at the sides. That spreading is why glaciers move forward.’

‘Got it.’

‘But because it’s spreading, the layers of ice don’t go anywhere. They just stretch out and get thinner — like the balloon. So in the centre, you can drill down and extract cores that sample every snowfall that’s ever happened on this glacier, one on top of the other. You can read them like tree rings. Fridge, for example, can analyse the air trapped inside the ice and tell you what the weather was like four thousand years ago.’

‘Core up,’ called one of the students on the drill. The cable stopped turning and started to reel in. The winch whined like a dentist’s drill; it took a long time to come up.

‘We’re about three hundred metres down right now,’ Annabel said.

A grooved steel pipe emerged on the end of the rope. Two of the students swung it out and laid it on a work table. They wore white clean-room suits; with the ECW clothing bulking them out underneath, they looked like abominable snowmen. They slid a cloudy cylinder of ice out of the tube and on to a sheet of plastic. They handled it delicately, like the fuse of a bomb. But they must have done something wrong: halfway out, the core cracked in two. Chunks of ice splintered off and dropped into the snow.

Annabel swore. ‘Brittle ice. It’s under so much pressure down there, when it comes to the surface it expands too quickly and cracks.’

While the students tried to extract the stump of the core, Annabel picked up the pieces that had fallen in the snow and dropped them into two of the Thermos cups. A small bottle of vodka appeared from inside her jacket.

‘Nothing like a glacier martini.’ The ice hissed and popped as the vodka covered it. ‘What you’re hearing is four-thousand-year-old air. It gets trapped when the snow falls; as the snow compresses into ice, the air gets frozen into it.’

I sniffed the cup. ‘Is it safe?’

‘Probably cleaner than what you’re breathing now.’ She laughed. ‘Fridge would kill me if he knew we were wasting it.’

I downed the vodka and felt the cold spreading through my stomach. ‘I heard he disagreed with Martin over some data.’

‘That was a different project — sea ice, over on the west side. Fridge was getting some anomalous readings so he asked Hagger what he thought.’

‘And didn’t like the answer.’

‘Hagger was a shit,’ she said suddenly. She tossed back the last of her drink. ‘He used people, and then he forgot them.’

The vodka had made me less cautious than usual. ‘Why did you let him go off on his own that day?’

‘I had work to do here.’

‘Couldn’t you have sent one of your grad students?’

‘He wanted to go on his own.’

‘Didn’t you care about the risks?’

A blush rose in Annabel’s cheeks. Behind her sunglasses, I felt her gaze harden.

‘I’ve got eight weeks on Utgard, and it’s costing my funding body two hundred pounds every hour I’m here. We work eighteen-hour days, seven days a week, freezing our arses off. And if you think that makes me sound like a workaholic bitch, Martin was just the same. He wanted to get the work done. I respected that.’

I backed off. ‘I’m sorry. I’m just trying to understand.’

‘There’s nothing to understand.’ She pointed to the drill rig. ‘I can tell you how much snow fell four thousand years ago, and Fridge can tell you if it was barbecue weather that year. But why Martin broke his neck on the Helbreen …’ She shook her head. ‘The data isn’t there.’

I remembered the sample I’d seen in Hagger’s freezer. ‘Did you do any ice coring on the Helbreen?’

‘Last summer. Nothing this year.’

‘But his work was on sea ice. Didn’t you think it was odd he wanted to go to a glacier?’

‘If I thought about every odd thing that people do at Zodiac, I’d never even get dressed in the morning.’ A gust of wind blew the cups off the packing crate. She pulled up her hood.

‘Would you like to be useful?’

I couldn’t very well say no. She handed me a spade and pointed me to one of her students, knee-deep in a hole.

‘Help Pierre dig out the snow pit.’

It was hot work, but I didn’t mind. Soon, I took off my coat and worked in my jumper, hat and gloves. I remembered how I’d seen Greta doing the same thing when I arrived at Zodiac, and how I’d thought she must be some kind of Inuit. Perhaps I was evolving.

We dug adjacent holes, separated by a thin snow wall that got taller as the holes got deeper. We talked as we worked. Pierre was a master’s student from Quebec, a lanky young man with a wide grin and a bandana tied over his head. He’d been here two weeks, had one more to go.

‘Looks like Annabel keeps you busy,’ I said.

‘Yeah.’

‘Two days ago, when Martin Hagger—’

‘That was too bad. He was a nice guy.’

‘Did anyone from here go and check up on him?’

‘Like, down to the Helbreen?’

‘Yeah.’

‘I don’t think so. We were all busy coring. Dr Kobayashi was away for a few hours checking the ablation poles, but that was it.’

He checked my side of the pit. ‘That’s deep enough.’

We squared off the two holes until the sides and floor were flat, taking extra care around the thin wall that divided them. Pierre put down his spade.

‘You wanna see something neat?’

He went off and came back with a square sheet of plywood. He laid it so that it half covered the hole I’d dug.