No one was going to chew him out for shooting a reindeer. He fired another shot into the air, scattering more scientists, then put the Remington to his shoulder and aimed at the shape in the fog. Even in the liner gloves, his fingers had got so cold they felt swollen fat. He squeezed the trigger again.

The mechanism clicked on a spent shell. He’d forgotten to chamber the next round. He pawed at the pump, ejected the shell and slammed in another round. Pulled the trigger.

It was a lousy shot. His finger wouldn’t bend, so he had to jerk the trigger with his whole arm, pulling the shotgun wide. Did he miss? The bear was still coming at him. He fumbled with the pump again, but his hand was so cold he couldn’t work the action. Fuck.

He looked up to see if he was going to die. The cloud shifted, like someone opening the drapes, and just like that he saw it clearly. Not a bear, or a deer. It was a man. Skiing over the ice in jerky, broken movements: lunging up, shuffling forward, then slumping down again, using the ski poles like crutches. He wore a red coat and black ski pants; a red fur-trimmed hood was zipped up over his face.

I nearly shot Santa Claus.

It must be one of the geeks gone off the reservation, lost his way in the fog. But the geeks didn’t ski. And they wore red pants, not black.

The man stopped as if he’d skied into a brick wall, almost falling over in his bindings. He threw out his arms and flailed his ski poles frantically; maybe he tried to say something, but either his hood muffled it or his voice was too weak. Without the poles to hold him up, he lost his balance and toppled smack into the snow.

Aaron laid down the gun and ran over. There was a name badge sewn on the jacket, Torell, and under it an insignia he didn’t recognise. A twelve-pointed star with a roaring polar bear in the middle. Next to it, blood leaked out from a nickel-sized hole punched through the fabric, crystallising almost as soon as it hit the snow.

Oh shit.

Footsteps floundered through the snow behind him. Lieutenant Commander Santiago, the ops officer, still in his ODU pants and a jacket he’d pulled on in a hurry. He stared at the figure on the ground.

‘Where in this godless white fucking hell did he come from?’

The man stirred; feeble clouds of air puffed off his lips as he tried to speak. Aaron put his head close. The fur tickled his cheek.

‘What’d he say?’ Santiago demanded.

Aaron looked up.

‘It sounded like Zodiac.’

The Terra Nova had the biggest sickbay in the Coast Guard fleet, but no doctor. Just a physician’s assistant, the PA, Lieutenant (JG) Carolyn Parsons. For most of the crew’s problems — splinters, scalds, sprains and sore heads — that was fine. For more serious cases, she could patch in the district surgeon on the video link. If that didn’t work, it was the helicopter or — worst case — a body bag and the cold-storage reefer.

But the video link was down, the helicopter had nowhere to go, and she was damned if she was going to lose her first major trauma. Even if it was more complicated than anything she’d been trained for. The manuals didn’t say how to treat someone for a gunshot wound and hypothermia at the same time. Lucky the slug had gone wide, taking a bite out of his arm but missing the bone.

He lay in a steaming-hot bath she’d rigged in the corner of the sickbay; a thermometer clipped to the side read 104˚ Fahrenheit. A saline drip snaked down from the ceiling and fed into his arm, just below the blood-soaked gauze pad strapped to his bicep. His clothes lay in a plastic basket on the floor where she’d cut them off him, together with a few things she’d found in his pockets.

He was a big man, even bigger than Commander Santiago. He couldn’t have eaten much on the ice — the only trace of food in his pockets was a Mars bar wrapper — but he was still in great shape. She’d needed two crewmen to help her hoist him into the tub. He didn’t fit full stretch, but lay on his side, his knees tucked up like a baby. A folded towel cushioned his head. His eyes were closed; the heat had thawed the ice in his hair and matted it flat, revealing a small scar behind his left ear. She guessed he must be about thirty.

‘What’s up, Doc?’ Santiago ducked through the sickbay door and leaned against the cream-painted bulkhead. ‘Is he gonna live?’

‘Most of him.’ She pointed to the patient’s right foot, where hard black boils blistered the skin. ‘Might need to take off a couple of toes. Too early to say just yet.’

‘He’ll walk funny for the rest of his life.’

‘He’s lucky to be alive.’ She checked the thermometer and ran more hot water. ‘Frostbite, hypothermia, exposure and a slug … Did he really ski all the way from Zodiac Station?’

‘Unless he got the jacket mail order.’ Santiago crossed the room and pulled down the jacket from the peg she’d hung it on. ‘Imagine, you come all that way and then a Coastie puts a slug in you.’

‘Semper Paratus.’

‘To fuck you up.’ He wiggled his finger through the hole in the fabric — then stiffened.

‘How many times did you say he got shot?’

‘Once was enough.’

‘Take a look at this.’ He brought the coat over and stretched it out between his hands. Just below the Zodiac Station badge, his finger poked through another hole. A broad patch stained the fabric around it a darker shade of red.

‘I did a tour in Umm Qasr. If I didn’t know better, I’d say that looks like the entry point for a thirty-calibre bullet.’

‘Then where’s the wound? If that was a bullet, it would have gone right through his heart.’ Parsons pointed to the man’s chest. ‘No damage. Plus, there can’t be anyone out there inside of a hundred miles from here.’

‘Maybe the polar bears got pissed off.’

A scream, like something from a horror movie, tore through the sickbay. The man in the bath was sitting up, legs tucked against his chest and eyes wide open. Water sheeted down his bare skin, as if the ice inside him had finally melted and was flooding out through his pores.

Parsons rushed over and tried to ease him back down into the bath. ‘You need to keep down, sir. If your extremities heat too fast, there’s a risk of heart failure.’

He resisted. Water splashed over the side and pooled on the floor. He was too strong; even half dead he couldn’t be moved against his will. Santiago came over, but she waved him back. You couldn’t force this.

‘Sir, if you don’t stay in the water, the warm blood in your extremities will flood back to your core and stop your heart. In your condition, it probably won’t start again.’

He stopped struggling. ‘It hurts,’ he groaned.

‘Hurts like a motherfucker,’ she agreed. ‘That’s a good thing. It means you’re alive.’

She pushed his shoulders down. He didn’t fight her this time; through clenched teeth, he let her add more hot water. His eyes followed the line of the IV drip up to the bag, then scanned the room. ‘Where am I?’

‘Aboard the Coast Guard cutter Terra Nova.’ It didn’t seem to register. She poured a cup of hot water from a flask and handed it to him. ‘You’re safe, Mr Torell.’

‘Anderson.’ His mouth could barely make the word.

‘I’m sorry?’

‘Anderson.’ He sipped from the cup. Blood from his cracked lips clouded the water. ‘My name is Thomas Anderson.’

‘Your coat — we assumed …’

‘The zip on mine broke.’

‘Whoever Torell is, I hope he has a spare,’ said Santiago.

The man called Thomas Anderson looked up over the rim of the cup. ‘He’s dead.’

Santiago exchanged a look with Parsons. ‘You want to tell us …?’

‘They all are.’

‘They?’

‘Everyone at Zodiac.’ He slumped back down into the bath so that the water covered his chin. Santiago reached for the phone.