But even the numbers couldn’t completely stifle Hagger’s personality. He hung around in the margins and the blank spaces, shouting from the sidelines even after he was dead.

Where is it coming from?

Why Why Why? (Double underlined.)

Maybe Anderson?

And, a couple of pages in, the line I’d read in the sickbay. Fridge will kill me.

‘Feeling better?’

You could have predicted who it would be. Fridge, still dressed in his ECW trousers. Not holding a fire axe or pointing a gun at me, just giving me his friendly Viking smile.

I remembered (or did I?) the man standing over me on the glacier. Fist raised to strike. Could it have been Fridge? He seemed familiar, but all my memories felt like half-truths that morning.

I snapped the notebook shut. Then I decided to go on the attack.

‘There’s something I’m trying to understand.’ I opened the notebook again and spun it around so he could see.

The smile vanished. I looked him in the eye, trying to squeeze out the truth. Maybe I’m not much of an interrogator.

‘I wish he hadn’t written that.’

‘It’s awkward,’ I agreed.

‘Kennedy already asked me about this. I shared some confidential results with Hagger; he got Quam on my ass saying I couldn’t publish.’

I spun the notebook back so it faced me. Above the smoking-gun sentence was a table labelled Me Concentrations, Echo Bay.

‘Methane,’ I guessed. ‘Something to do with the DAR-X drill site?’

Fridge didn’t contradict me.

‘Methane gets produced by the breakdown of oil in water.’

He gave me a grudging nod of respect. ‘Can do. Or, hypothetically, if you’re pretending to pump oil, but actually drilling for methane clathrates in the seabed.’

‘Hypothetically?’

‘Hypothetically unless you want to be sued for violating commercial secrecy.’

‘Was Hagger’s work commercially secret?’

Fridge shook his head wearily. ‘He didn’t even care about the methane. He just found it out by accident.’

‘What was he looking for?’

‘Bugs,’ said Fridge. ‘Bugs in the water. Something corroding DAR-X’s pipes. Hagger found a bug in the water munching them.’

‘What sort of bugs?’

He shrugged. ‘You should talk to K-Mart.’

I looked out the windows, confused. ‘Where’s K-Mart?’

‘The guy you replaced, Hagger’s old assistant. Kevin Maart, so we called him K-Mart. He must have helped Hagger.’

The room was filling up with students drifting in for lunch. I could smell lasagne, and I was ravenous.

Fridge gave an odd laugh. ‘But maybe K-Mart didn’t know anything. If he had, Hagger wouldn’t have brought you.’

I ate quickly and messily. It’s hard to linger over a meal when you’re staring round the room wondering if someone could really want to kill you. Hard to keep the soup on your spoon if your hand won’t stop trembling.

Afterwards, I stopped off in Quam’s office and asked him if he knew how I could contact Kevin Maart.

‘I can’t tell you that.’ Every time he speaks, he makes you feel you’ve done something wrong. ‘Data protection.’

I told him I just wanted to check out a couple of things that Hagger had been working on. That seemed to upset him even more. He set his perpetual-motion toy going, staring at it as if he could glimpse something profound in the spaces between the swinging balls.

‘You’re supposed to rest. If it weren’t for these …’ click ‘… regrettable …’ clack ‘… circumstances, you wouldn’t even be here.’

‘I thought I might make myself useful.’

‘Don’t. Just …’ click ‘… keep out of trouble.’

There were a lot of things I’d have liked to ask him. Like: Who killed Hagger? Or, given how fidgety Hagger’s research made him: What happened to his notebooks? But I didn’t think bringing any of that up would count as keeping out of trouble.

‘Did you ever set me up a login account on the network?’ I asked.

His eyes narrowed, as if I’d asked for his PIN. ‘Didn’t get round to it.’ He was trying to sound casual, though that was a stretch. ‘Now you’re leaving, you don’t need it.’

‘I’ll be around for a few days yet.’

He acted as if he hadn’t heard me. ‘How’s your head?’

‘Better, thanks,’ I said, through gritted teeth. ‘But about the login account …’ I relaxed into the chair with an appreciative sigh. The sound of a man who might be there some time. Quam took the hint. He got a piece of paper from his desk and slid it across to me.

‘Fill this in and get it back to me.’

Quam’s martinet routine annoyed me — especially as data protection’s a rather anachronistic concept these days, given what governments get up to. I went to the radio room, logged in to the guest computer and googled Kevin Maart. I found his home page at Cambridge, his publications record. Rather more impressive than mine, to be honest: if we ever run into each other, I’d be embarrassed to say I took his job. It also gave a phone number, and an email address: kevin.maart@zodiacstation.org.uk.

He wouldn’t be checking that any time soon. Obviously he hadn’t updated it yet. I wrote an email anyway, just in case. It amused me to think of it travelling halfway around the world, and pinging into the room next door.

I took one of the Iridium phones from the charging shelf and rang the number on the website. Quam would hit the roof, no doubt, at the cost of it.

A receptionist answered. ‘Kevin Maart’s away in the field,’ she told me.

‘He flew home a week ago.’

‘He hasn’t been back in the office.’

Strike two. I asked if she had a mobile number for him. Perhaps she did, but of course, she couldn’t give that out. Data protection.

I took the notebook back to Hagger’s lab to see if I could make more sense of it in context. I looked in the fridge and found the samples he’d left there: forty-three of them, clear plastic bags filled with water, each numbered and dated with a white sticky label. Also, I noticed, each one had a round dot coloured in on the label, either red or green.

I turned through the notebook until I found a list of samples whose reference numbers matched the bags. Beside each one, he’d written down where he’d taken it. Helbreen. Helbreensfjord. Echo Bay. Nansen Bay. Luciafjord. Konigsfjord.

Some of those places I knew; most of them I didn’t. I went to the bookshelves in the mess and rummaged through the thrillers and potboilers until I found a survey map of Utgard. I spread it out on Hagger’s lab table. It had been made in the sixties, but I didn’t suppose Utgard had changed much. I worked my way over it, marking the location of each of Hagger’s samples with pencil X’s. It reminded me of being home with Luke, drawing treasure maps together.

As soon as I’d finished, it was easy to see where Hagger had been. A row of X’s ran down the west side of the island, with a cluster in Echo Bay and another up at the Helbreensfjord, where the glacier met the sea. More sporadic samples made a dotted line along the coast, north to the tip of the island, and as far south as Zodiac, where they grouped in another cluster. A single spur branched off up the Helbreen glacier, regularly spaced X’s until they reached more or less the place where Hagger had died, with a couple more on the other side of the mountain, near a place labelled Mine 8.

I found green and red marker pens in one of Hagger’s drawers. Cross-referencing the samples and the notebook, I circled my X’s on the map red or green, whichever colour Hagger had marked the bags. I also wrote in the dates. Then I stood back and examined my work.

The red circles made a bone shape, with clusters at Echo Bay and at Helbreensfjord, and a thinner stretch along the stretch of coast connecting them. North of the line, and south down to Zodiac, they turned green.