Quam liked to say that in a place like the Arctic, procedure will save your life. Ever so pompous, but it’s true. Procedure says that any party in the field has to carry a survival pack, and in that pack there’ll be a thirty-metre length of nylon rope. Eastman fetched the pack and found the rope.

‘Can you tie it round yourself?’

I shook my head. I hadn’t stopped shaking since he got there. He frowned.

‘OK.’

He tied a carabiner to the rope end, so I could clip it around me without having to knot it, and tossed it to me. He looped the rope over the steel hawser, wrapped a couple of turns around one of the wooden posts, and lowered me to the ground. Not gentle, but I was in no state to care. I almost kissed the ground when I landed.

He dragged me to the nearest building and found a room where the walls were tolerably intact. It wasn’t any warmer than outside, but he shoved me into the bivvy bag and got the MSR stove going. We didn’t speak. For now, the priority was survival. The blood coming back in my hands made me cry out in pain: they’d look pretty ugly in a week or so. At least I had feeling.

Eastman warmed some chocolate between his hands for me, and chipped icicles off the building outside. While they melted, he made me a cup of sweet tea with water from our Thermos. The heat from the cup sent tremors through my hands; when I sipped it, I thought my teeth would explode. I forced it down.

‘You picked one hell of a time to play hide and go seek,’ Eastman said.

I told him everything that had happened. I didn’t think he’d believe me — with a cup of tea in my hand, I hardly believed it myself — but he never challenged me. I was grateful for that. If anything, he seemed slightly distracted. He kept glancing at the door. Perhaps he was worried the gunman would come back. I certainly was. Each time the ice popped and cracked in the pot, I imagined a heavy footstep on the stairs, that faceless man approaching through the rotten building.

‘DAR-X wear yellow jackets,’ Eastman said when I’d finished.

‘I thought of that too.’

‘You didn’t recognise him? From when we visited Echo Bay?’

‘There wasn’t much to go on.’

The water had finally melted and boiled. He made me another cup of tea, then poured the remainder into two of the dehydrated meal packs.

‘I called Jensen. He was heading back to Zodiac. He has to refuel, then he’ll come right out. Should be a couple of hours.’

I lay back in the bivvy bag. A blissful glow had started warming through me. If I closed my eyes I saw euphoric white light.

Don’t go to sleep, I warned myself. The gunman was still out there. So, for that matter, was the bear. I forced my eyes open.

Across the room, Eastman was giving me a crooked look.

‘What?’

‘There’s another option, of course.’

‘Another option for what?’

‘There’s how many people on this island? A couple dozen, maybe thirty if you count the students? That guy who just tried to kill you, he’s still around. Do you want to go back to Zodiac, wait until he finds us again?’

Extraordinary question. ‘I want to go back to Zodiac so I can get away from him.’

‘Or do we try and get him where we know he’s at?’ Eastman leaned forward, a predatory set to his jaw.

‘Get him?’ I repeated. ‘I’m not John Wayne.’

Eastman picked up his rifle and squinted down the sight. ‘We’ll be ready for him.’

‘And what makes you so sure he’ll come back?’

A bright white grin. Wolfish, you might say, if wolves had access to modern orthodontics.

‘Because you’re still alive.’

And that seemed like a fine reason to go home. Quit while I was ahead. It’s a thin line you walk in the Arctic at the best of times, and I’d very nearly gone over the edge. I needed food, warmth and rest. Then there was the matter of my patients, Anderson and Trond, who needed my care back at base.

But I’d spent days blundering around, and it had nearly killed me. The figure on the cableway terrified me, true, but running away wouldn’t cure that. The only way to escape — really, truly escape — was to get answers.

Eastman called Jensen on the satphone and said we were spending the night. ‘Tell Quam we’ve got high winds at Vitangelsk. We’ll let you know when it’s safe.’

I heard Jensen’s surprise through the speaker. It must have been a calm day at Zodiac.

‘Just tell him,’ Eastman said, and rang off.

‘Do you trust Jensen?’ I asked.

‘What do you mean?’

I hesitated. I’d spoken without thinking — but now that I had, I wanted to go on. I was too tired for games. And Eastman had saved my life.

‘Someone at Zodiac’s been leaking information to the oil companies,’ I began. ‘Whoever it is, I think that person killed Hagger — either because he was in on it, or because he found out.’

It was the first time I’d mentioned the possibility of Hagger’s murder to him. He didn’t look shocked, not even surprised. He must have been thinking along the same lines.

‘Are you sure?’

‘Hagger was moonlighting for DAR-X,’ I went on. ‘They were up here the day he died, and then they kindly helped bring in his body.’

‘So they were in the same place. Why would they go for Hagger?’

‘You know, it’s not oil they’re drilling at Echo Bay. It’s something called methane …’ I stumbled over the word ‘… clathrate. So bad, it’ll make oil and gas look like eco fuels.’

‘Who told you that?’

I decided to leave Fridge out of it. ‘Hagger found out. I don’t know who else knows. It might be a secret worth keeping.’

Eastman took a silver hip flask out of his coat. ‘JD. You want some?’

I demurred. He took a long swig. ‘If you’re right — and it sounds kind of crazy to me — then Hagger must have been acting alone. He was the only one of our guys up this end of the island that day.’

‘He wasn’t.’ I sat up in the bivvy bag and leaned forward. ‘Ash was, too. Jensen dropped him off right here in Vitangelsk.’

For the first time, I sensed he might be taking me seriously. ‘Jensen kept that quiet.’

‘Ash warned him he’d get in trouble if he told.’

Eastman put away the flask and picked up the rifle. Working quickly, hardly looking, he unclipped the magazine and ejected the cartridges.

‘You think the guy on the cableway could have been Ash?’

I’d wondered. ‘He seemed too big. It was hard to get a good look.’

‘Maybe we’ll get a better view tonight.’ Eastman reloaded the magazine, pressing the bullets down one by one with his thumb. He snapped it back into the rifle and chambered a round.

‘I’ll keep watch. You get some rest.’

As well as the rifle, he kept a flare pistol strapped to his thigh — a snub black thing that looked like a child’s toy. He loaded a flare into the pistol but left it broken open. He put it on the floor next to me.

‘For you. Just in case.’

I didn’t sleep well. My hands ached like an old lady’s; even in the bivvy bag, I couldn’t stop shivering. With my eyes open, the room seemed dark and dim; when I closed them, the night seemed far too bright. Every creak in the building had my imagination working overtime. And every time I started to drift off, the man in the yellow parka reared up in my mind’s eye like a bear, killing my dreams before they began.

But I must have fallen asleep — or I wouldn’t have woken up. Eastman was shaking my arm. The first thing I saw was the rifle on his shoulder.

I glanced at my watch: 4 a.m.

‘What is it?’

‘Come and see.’

I’d slept fully clothed. I pulled on my boots and gloves, and followed Eastman out the door. Even that close to the twenty-four-hour day, some primitive part of my circadian clock picked out the signs of morning: the empty streets, the dewy silence.

I was fooling myself. A ghost town’s streets are always empty, and there hasn’t been dew on Utgard for about ten million years. In the distance, I heard a faint drone like a buzzing fly.