‘You can take it to the North Pole,’ he explained.

I tucked it in my pocket and kissed him goodbye.

‘Don’t get eaten by the polar bears,’ said Lorna.

I flew to Oslo, then to Tromsø, where I had a ham and cheese sandwich and transferred on to a small Twin Otter for the last leg to Utgard. There was no one else on the flight, just me and the pilot and a couple of tons of supplies.

I suppose you know about Utgard. It’s the last place in the world, the most northerly scrap of land on the planet. Easy to miss — so easy, in fact, that no one realised it was there until the twentieth century. Most of it’s covered in ice, so much that the weight has actually pushed the land below sea level. Not that there’s much sea, either: for ten months of the year it’s frozen solid. The only notable population is polar bears, and a couple of dozen scientists at Zodiac Station. I wouldn’t like to say who’s hairier.

Even from Tromsø, it took another six hours’ flying. We refuelled at the base at Ny-Ålesund, where the mechanics fitted skis to the plane and the pilot changed into his cold-weather gear. He gave me a dubious look, in my jeans and the jacket I use for walking the Broads with Luke.

‘They said they’ll issue me clothing when I get there,’ I explained.

‘Then hopefully we get there,’ he said. I took it as Norwegian humour.

We carried on north. I stared out the cockpit window, keen for my first sight of Utgard. Behind the clouds, dark patches swam in and out of view, like bruises forming under skin.

‘Will we be able to land?’ I asked. The pilot shrugged. Was that another joke?

My first view of Utgard was a swelling on the horizon, white peaks almost impossible to tell apart from the clouds. As we got closer, they resolved themselves into mountaintops. The clouds parted on a dramatic landscape, a Toblerone rampart guarding the western approach. The island was such a small dot on the map, it was hard to believe so many mountains could fit on it. They seemed to go on for ever.

We descended between the mountains and skimmed over a white fjord. The pilot banked, turned, and suddenly I saw two rows of red flags staking out the runway like drops of blood. The plane thumped down, bounced slightly, and skied to a stop. Considering we’d landed on solid ice, it was pretty controlled. Outside, I saw a limp windsock, a clutch of oil drums and an orange Sno-Cat. Otherwise, just mountains and snow.

‘Welcome to Zodiac,’ said the pilot.

The cold sank its teeth into me the moment I stepped off the plane. At the foot of the ladder, I saw a woman rolling an oil drum towards me. The first thing that struck me was that she wasn’t wearing a coat: just a thick knitted jumper, ski trousers, and a woolly hat with tasselled flaps covering her ears. A long blonde plait hung down her back. Her cheeks were flushed red with the cold, and the eyes that looked up at me were a cool ice-blue.

‘Tom Anderson,’ I introduced myself.

‘You’re in the way,’ she shouted, though I could barely hear her. The pilot had left one of the engines running, and the propeller almost drowned her out. So much for the silence of the Arctic. I scrambled out of her way and stood on the sidelines while she and the pilot ran a hose from the fuel drum to the plane. When that was secure, the pilot climbed in the cabin while the woman reversed the Sno-Cat up to the door. The pilot began sliding out the boxes of supplies we’d brought, which she loaded into the back. They seemed to have forgotten I existed.

I wanted to savour my first sight of the Arctic, but it was hard to concentrate. The cold squeezed my skull; my ears hurt as if they’d been slapped, and the icy wind made my eyes water. The propeller racket beat against me, and every breath I took was heavy with aviation fuel. I had gloves on, but they might as well have been tissue paper.

‘If you freeze to death before you sign the paperwork, the insurance doesn’t pay out,’ said the woman. I hadn’t noticed her come over. She grabbed my arm and dragged me towards the Sno-Cat. I couldn’t believe how useless I’d got so quickly: I couldn’t even lift myself into the cab without a shove from behind. But the engine was on, and the heater made the cab decently warm. I didn’t like to think what all those engines running non-stop must be doing to the atmosphere. At that moment, I didn’t care.

The woman climbed in and circled the Sno-Cat round, while the Twin Otter executed a quick turn back down the runway. In an impossibly short distance, it lifted off and disappeared behind the mountains.

‘I hope you didn’t change your mind,’ said the woman. I still hadn’t caught her name.

‘Tom Anderson,’ I introduced myself again.

She nodded, and kept on driving.

‘What’s your name?’

‘Greta.’

‘How long have you been here?’

‘Two years.’

‘Must be tough,’ I sympathised.

‘I like the silence.’

I took the hint. The Sno-Cat ground and bounced its way over the snow. Round the base of an outcropping mountain, into a low valley — and suddenly there was Zodiac.

It looked like a spaceship landed on an alien planet. The main building was a low, green oblong jacked up on spindly steel legs. A white geodesic dome bulged out of the roof; the rest of it was covered with a mess of masts, aerials, satellite dishes and solar panels. Subsidiary buildings clustered around it: a mix of faded wooden huts in assorted sizes, curved-roofed Nissen huts, and bulbous orange spheres with round portholes, like deep-sea submersibles left behind by a sinking ocean. Flags fluttered from a line of red poles that staked the perimeter, a shallow semicircle down to the frozen edge of the fjord.

We pulled up outside the main building — the Platform. It was bigger than it had looked from the top of the hill, almost a hundred metres long, with a jumble of crates and boxes stored underneath. A flight of steel steps led up to the front door.

A low bang rolled down the valley as I stepped out. I glanced over my shoulder.

‘Is that thunder?’

‘Seismic work,’ said Greta. ‘They’re blasting on the glacier.’

We climbed the steps. On the wall by the door, a scratched and faded plaque said Zodiac Station; under it, a much brighter sign added, British South Polar Agency. It looked like the newest thing on the base.

‘Did I take a wrong turn somewhere?’ I looked around, half expecting to see penguins.

‘New management.’

Greta kicked a bar on the base of the door and it swung in. All the doors at Zodiac opened inwards — to stop drift snow trapping you. Inside was a small, dark boot room, and a second door opening further in.

‘No shoes in the Platform,’ said Greta. She turned to go.

‘Wait,’ I called. ‘Should I introduce myself somewhere?’

The door slammed behind her.

I left my boots and coat in the vestibule and ventured through the next door. The first thing I saw on the other side was a gun rack bolted to the wall: half a dozen rifles standing upright, more spaces where others were missing. Beyond, a straight corridor ran for what seemed an eternity, dozens of doors but no windows. It reminded me, unpleasantly, of the set of the Overlook Hotel. You know, from the film The Shining. Stanley Kubrick directed it.

I padded down the carpeted corridor in my socks. I read the signs on the doors I passed, little squares of card that seemed to have been typed on an honest-to-goodness typewriter. Laundry Room; Dark Room; Radio Room; laboratories, numbered in no particular order I could work out. One said Pool Room, and under it someone had taped a holiday-brochure photo of an azure-blue swimming pool. I opened it, out of curiosity, but there was only a half-size pool table crammed in a windowless cupboard.

Further along, I found the door for Hagger’s lab. On a sheet of A4, a red skull and crossbones warned HIGH INFECTION RISK OF UNKNOWN DNA. Undeterred, I knocked and when no one answered I went in. None of the doors at Zodiac have locks except the toilet (and that had broken).