She grabbed his arm and pulled him away from the rest of the refugees, who had finally realized they weren't in immediate danger. The rest of the squad kept their weapons raised regardless; terroristas had a habit of hiding amongst those fleeing from the fighting.

A military transport of similar design to the air-ambulances dropped down towards the road that ran parallel to the top of the embankment.

'Kellogg said you'd run off in the middle of a fucking combat zone!' Karen shouted at him. 'I mean, what the fuck was going through your head?'

Nathan found he couldn't frame an answer, so he remained mute as she tugged him towards the steps, and the beckoning lights of the transport waiting above. Several minutes and a dozen kilometres later, the same transport dropped down towards a camp that spilled out along the streets lining both sides of Third Canal. Smoke rose from clusters of tents and prefabs where a sea of refugees warded off the freezing cold by burning furniture and anything else combustible. These were the lucky ones, awaiting immediate evacuation; in the surrounding city, there were tens of thousands dying more slowly of starvation or freezing inside their homes.

The transport's lights picked out the landing pad on the roof of the clinic and began to drop towards it. Nathan glanced out of a window and saw in the distance the great flickering wall of energy that delineated the nearest perimeter of the coreship's human-habitable zone. Closer to hand loomed the black shape of one of the sky-pillars, a great, carved rock limb that was only one of hundreds supporting the coreship's outer crust. 'Hey Nathan, you stupid bastard. Wake up. It's me. Karen.'

Within minutes of disembarking from the ambulance, he'd crawled on top of a spare trolley in the clinic, and passed out. He groaned and sat up, blinking in the harsh lights and rubbing at a sore spot on his arm.

Karen regarded him with a mixture of scorn and pity. She'd taken off her helmet and matte-black body armour and let her hair fall down to her shoulders. One of the doctors stood next to her, a dark-skinned woman in disposable paper clothing.

The clinic, unlike almost anywhere else currently in Ascension, was warm. The doctor leaned in towards Nathan and pulled one of his eyelids up, shining a bright light directly into his pupil.

'Seems okay,' she remarked, her voice brisk. She then took out a hypo and aimed it towards Nathan's arm, almost before he realized what she was doing.

'Hey!' he shouted, sliding off the trolley and out of her immediate reach.

The two women stared at him with almost identical expressions of exasperation.

'For God's sake, Nathan,' said Karen. 'Doctor Nirav is trying to help you.'

'Thanks, but I don't need any shots.'

'What, you fucking phobic or something?' she replied in a voice full of scorn.

'Command think Peralta's got his hands on some kind of nerve agent,' explained Nirav. 'That means everyone gets a shot, and we also take a blood and DNA sample at the same time. Everyone has to do it, no exceptions.'

Nathan glanced warily towards the doctor. 'Forget it. No samples of any kind, either.'

'Why the fuck not?' asked Karen.

'Sorry,' said the doctor, patting a pocket. 'Got that already while you were out cold. So how about you stop whining and take the shot now, so I don't have to get some of the guys from security to come here and hold you down while I give it to you anyway?'

He hesitated, and even thought about making a run for it and taking his chances outside before they could identify him from his DNA sample. But where could he go? His work as a medic had given him a sobering overview of just how bad things were in the city; outside lay only a cold and hungry death.

Instead he nodded, and Nirav pressed something cold against his neck. There was a hiss and a sudden jolt of pressure against his skin, and then it was over.

A block of ice immediately settled into the pit of his stomach. It had only ever really been a matter of time before they worked out who he was, and there was literally nowhere he could run.

As Nirav departed, Karen folded her arms and studied him with a mixture of motherly concern and mild contempt. 'To be honest, Nathan, after the way you ran off back there, I was worried maybe you'd caught a whiff of that nerve gas and gone crazy. Who was it you said you saw?'

Nathan shook his head. 'I made a mistake.'

She sighed and reached out to tug him closer to her. 'How awake are you?'

'Not very.'

She shook her head. 'Not the right answer,' she said, pushing a hand through his hair. 'It's been a long day, Nathan. Let's go back to my place.' What Karen called 'her place' was a room in a commandeered administrative block on the other side of the main refugee camp. She had cleared it of most of its remaining furniture, whatever hadn't already been burned or looted, and had installed a spare cot from the clinic. Technically this was against the rules, but nobody seemed to care enough to enforce them. The illicit arrangement did have the advantage of giving her and Nathan some privacy.

A small portable heater glowed in the dark nearby, illuminating Karen's warm lithe body from behind her. Nathan slid his hands around her waist, then moved them up to cup her small breasts. Her tongue felt wet and salty as it licked against his lips. He felt himself stiffen, a wave of sudden, needful ardour washing over him.

She grinned and slithered expertly on top of him, quickly sliding him inside her. She was already wet. Her hands pressed down hard on his chest, the sensation almost painful, then she began to move, her hips grinding slowly.

Even the building's basement generators, augmented by their tiny heater unit, could not together quite keep the cold out, and soon he shivered, his skin prickling in the frigid air. He thought of the bodies he'd seen floating along the canal, picked out by the rover's unforgiving searchlights, and felt his ardour begin to fade.

'I'm not sure I can,' he muttered, and felt a sudden wave of fatigue wash over him. It had been, as she had said, a long day. 'Maybe we should try and get some sleep.'

'Shut up,' she said, her voice ragged, hands pressing ever more forcefully against his chest. 'Don't disobey the orders of a superior officer.'

I'm not in your fucking army, he thought. But he dutifully held on to her plump thighs and banished those images of death and decay from his mind, concentrating instead on the tumble of her hair across her shoulders and the moistness of her lips when she leaned down to kiss him. To his surprise it worked, and he listened to the increasing hoarseness of her breath just before she climaxed and came to a gasping halt. Her head tipped back, before she finally collapsed against his chest.

'Oh fuck, I needed that,' she moaned.

'You're welcome,' Nathan muttered. He glanced towards the window, where he could see the underside of a sky glowing a dull red.

Karen slid back down beside him and lay there for a few moments, her head resting on his shoulder. He sensed something else was on her mind and, after a few minutes of silence, she pushed herself up on one elbow and stared down at him.

'So who was she?' she asked, regarding him with a serious intensity.

Nathan gazed at her blankly until he realized she meant Ilsa. 'What makes you think I was looking for a she?'

'Intuition.' Karen's expression softened a little and she smiled. 'I'm not saying you have to answer. I'm just curious.'

'Does it matter?'

'You know, Nathan, it doesn't take a genius to guess you're hiding something.' She rolled on to her back beside him and sighed. 'I guess there's never going to be a good time to tell you this.'

'Tell me what?'

'I'm being reassigned. They're sending several new expeditions into the rest of the coreship, and I've been asked to join one. We might even try to penetrate the command core this time round. It'll be a joint operation, undertaken with the surviving Skelites and Bandati in the other zones.'