‘Greta’s spoken to him. He knows you’re OK.’

‘Right.’ He lay back, wincing as his head touched the pillow. I put two paracetamol in a cup and popped it on the table next to his bed. He stared at the ceiling.

There was something I was dying to know. ‘Up on the Helbreen — when you fell. Do you remember that?’

‘I didn’t fall.’ Behind those eyes, the clouds parted. ‘Someone came at me.’

‘There wasn’t anyone there,’ I told him. ‘Except Annabel.’

He frowned. ‘She’d gone behind the rocks. For a wee. Someone hit me from behind.’

All my suspicions about Annabel came back in a flash — her and Hagger, her and Anderson. But I couldn’t make myself believe it. She’d brought Anderson back to Zodiac, after all. Rescued him. If she’d really wanted to kill him, she’d gone about it all wrong.

‘You fell in a moulin,’ I corrected him. ‘Didn’t watch where you were going — banged your head.’

‘Someone hit me from behind.’ His eyes narrowed, focused on something far away.

‘Must have been a dream. You’ve been asleep for two days, head stuffed full of bumps and drugs. It’s normal you’re a little confused.’ I got my ophthalmoscope and shone the light in his eyes to check for concussion.

‘I found a notebook,’ Anderson said. ‘I was reading it.’

So much for short-term memory loss. I wondered what to do. I still wasn’t sure if Anderson was on the level. At that stage, I didn’t trust anyone.

If you ratchet up this paranoia any more, someone’s going to crack. Maybe Quam was right. My body was already starting to tell me it wanted another diazepam.

I opened my cabinet. As I took out the notebook, I saw the burnt corner of the other notebook I’d found at the cabin. Does Ash know where it’s going? I hid it under the prescriptions book.

‘I had a flick through. Couldn’t make much sense of it,’ I said casually.

He turned a couple of pages and raised an eyebrow. ‘“Fridge will kill me,”’ he read aloud.

‘A figure of speech. Martin did some work for DAR-X. Fridge thought that was sleeping with the enemy.’

‘And all this about “X”. “Concentration of X”, “dispersal of X” … Do you know what “X” is?’

‘I was hoping you could tell me.’

I thought about what Quam had said. Hagger was a busted flush. Did it make any difference what he’d written in his notebook — or was it all fiction?

I excused myself to check on the pilot, Trond. Halfway down the corridor, I ran into Jensen.

‘Can I have a word, Doc?’ I nodded. ‘In private?’

‘Of course.’

There was no privacy in the medical room; we went to the pool room. It used to be a store cupboard, but one winter some bored technician made a half-size pool table out of old packing crates and crowbarred it in. The cues were flagpoles that had been machined down; the felt from old boot liners. I can’t imagine where he found the balls.

There was barely room for two people to stand either side of it, let alone to wield a cue. But it was tolerably private, and no one ever went in there outside the annual pool tournament. I leaned against the door to keep it shut, while Jensen spun a ball on the table.

‘There’s a rumour going around,’ he said. ‘Hagger — they’re saying it wasn’t an accident.’

I didn’t need to ask how the rumour had started. If Danny had heard me in Quam’s office, everyone on Utgard would know by now. Eastman’s instruments had probably picked it up from space.

‘Ask Quam,’ I told him.

‘Do you know who’d have done it?’

‘No.’

With a flick of his wrist, he sent the ball rolling towards one of the pockets.

‘I think I do.’

The ball dropped in the pocket. Lost in my thoughts, I almost missed what Jensen had said: I was too busy thinking about Annabel and Anderson and Fridge and Quam.

Then it registered.

‘You know who killed Hagger?’ I said stupidly.

‘That day — when Hagger died. I said I was flying Dr Ashcliffe all day looking for polar bears.’

I nodded.

‘It’s not true. Not all true. We were out there, but we didn’t have much luck. Mid-morning, he told me to drop him off. He thought he’d have a better chance watching and waiting on the ground.’

‘Where was that?’

‘The Russian mining town. Vitangelsk. I went off by myself, restocked a few of the fuel depots.’

‘How long were you gone?’

‘Two hours. Maybe three.’

‘Can you check the flight log?’

He picked at the felt on the table. ‘Ash said I should write it up as if we’d been flying all day.’ He saw the look I was giving him. ‘It didn’t hurt anyone. The company bills the scientists for the time they book. They have to pay even if they don’t use it.’

‘You falsified the flight log? To hide the fact that Ash was on his own all afternoon?’ Vitangelsk is the other side of the mountain from the Helbreen; no distance at all. Ashcliffe could have skied it easily. If DAR-X hadn’t given him a lift.

Jensen looked miserable. ‘I didn’t think it mattered.’

‘Hagger died that afternoon,’ I reminded him.

‘Jesus, you think I don’t know? But we all heard it was an accident. I didn’t think it could’ve been anything else, until today.’

I backtracked. ‘How did Ash seem when you picked him up.’

‘That’s the thing. He looked pretty shaken up, said he’d had a close encounter with a bear.’

‘A bear?’

‘But that’s not all.’ Jensen glanced at the door and leaned over the pool table. ‘He had blood on his coat.’

Does Ash know where it’s going? Suddenly the words in the notebook took on a whole new meaning. I’d thought so hard about Fridge and Annabel, I’d never really considered him.

‘He had blood on him?’

‘Big smear, right along the sleeve.’

‘You didn’t wonder—’

‘He said he’d had a nosebleed.’ Jensen caught my eye; despite the situation, we both laughed. ‘Well, the air’s pretty dry up here.’

I thought about Hagger’s body in the deep freeze. I hadn’t seen any wounds on him. Even so …

‘Where’s Ash now?’

The field logbook said Ash had checked out an hour ago, headed out on the sea ice in the fjord. Going to confront him didn’t exactly fit with Quam’s instructions to let this go, but that didn’t bother me. I wanted the truth.

‘You’ll have to come too,’ I told Jensen. ‘I need you to back up what you told me.’

He edged away a fraction. I wondered if he was having second thoughts.

‘Eastman’s booked to fly in half an hour. Up to Vitangelsk. I’ll be gone most of the day.’

I made a quick decision. I hadn’t completely forgotten Quam: if I was going to accuse Ash of anything, I needed all the evidence I could get. He’d been at Vitangelsk that day; so had DAR-X. What if they’d left something behind?

‘I’ll come too.’

Jensen glanced nervously towards the medical room. ‘Shouldn’t you be taking care of your patients?’

‘Some painkillers will see them right.’

I filled some Thermoses with hot water from the kitchen. On the mess door, the Daily Horrorscope had been updated: Your plane is going down and your parachute is on fire. Sometimes it could be quite witty, but I thought that was in poor taste. You know, I still have no idea who wrote them. Never saw anyone put them up.

One day at school, in biology, they showed us a human skull. I’ve never forgotten the shock of it, the hollow cavity that had once been stuffed with life. Vitangelsk was a bit like that. The Russians had built it overlooking a snowy valley, tiers of barrack dormitories staring out from the face of the mountain. As we flew closer, you could see the sunken roofs and all the broken windows. Steel gantries teetered over the scene, waiting to fall. To the west, a line of wooden pylons stalked across the long ridge that led to the mine. They’d been part of the cableway that carried buckets of coal from the mine to the processing facility at Vitangelsk.