The next day, Andrew woke up with a headache.

     He sat up in bed. He'd had headache before, and raising his head sometimes helped ease the discomfort. This time, though, it didn't. In fact, it made him feel worse. His head swam with dizziness and his limbs trembled. He felt cold, but when he raised his hand to his forehead he found that he was feverish. Dammit! he thought. I'd better not have caught something from that cow after all.

     He looked down at Susan, still asleep beside him, and was alarmed to see that her face, what he could see of it under her tangle of auburn hair, was pale and sweaty. He brushed the hair from her face to feel her forehead and found it to be hot. Andrew felt his stomach clench with fear.

     Andrew's touch woke Susan up. "Andy?" she said. "Whoo, I feel funny."

     "Headache?" asked Andrew. Feel shivery?"

     "No," Susan replied. "Not really." She tried to sit up and her eyes widened with alarm. "Okay, now I've got a headache. Did we get food poisoning from that cow?"

     "I'll go check the kids," said Andrew, climbing out of bed. A wave of dizziness came over him and he leaned against the bedside table until it passed. Then he hurried to the children's room. He tapped on the door, then went in without waiting for an answer.

     All three children were hot and feverish. "Are we sick?" asked David, pulling the bedsheets up to his neck. "I feel hot and cold at the same time."

     "My arms ache," said James, turning over onto his side and pulling his knees up to his chest. "All my joints ache. Was it the cow? You said we might get sick. Nobody listened." He glared across at Jasmine who stared guiltily back at him.

     "Not to worry," said Andrew, trying to smile reassuringly. "We've got plenty of medicine in the stores. We just picked up a bug, that's all. A dose of antibiotics and we'll be right as rain." He patted the back of Jasmine's hand. "This isn't your fault," he told her. "You mustn't blame yourself."

     "Joe," said Jasmine, her eyes wide with terrible guilt. "He said... He told me..."

     "We're going to be fine," Andrew assured her. "You just relax and take it easy. Chances are we'll feel like hell today and be right as rain this time tomorrow. That's the way it usually goes. And if it does turn out to be a little more serious than that, we've got the antibiotics."

     "We'll need a proper diagnosis first," said Susan, who'd followed him into the room. "I'll go get the medical expert system going. No, on second thoughts, I'll put some clothes on first. I'm freezing!"

     "Stay in bed," Andrew told the children. "Keep warm. You all got bedside drinks? They say you should drink plenty of fluids."

     "I don't think I'd be able to keep anything down," said David. He tried to climb out of his bed.

     "Stay where you are," said Andrew, putting a hand on his shoulder and pushing him back down. His skin was alarmingly hot and sweaty, and yet Andrew could feel him shivering.

     "I can help you," insisted Jasmine, reaching for her underclothes.

     "We don't need any help. You just keep warm."

      Jasmine nodded reluctantly and lay down again, closing her eyes. Andrew looked around at the three children again, trying to look confident and to keep the desperate worry from showing on his face. Then, feeling weak, his joints aching, he returned to his own room to pull on some clothes.

     Susan had managed to put on her underclothes, and had then had to sit down to rest before reaching for her coveralls. In the meantime she'd called Philip and Lungelo and their faces on the screen, pale and sweaty, showed that they were in the same condition. "We've all got it then," said Philip, frowning with worry. "Stacey's in a really bad way. I'm really worried about her. Valentina's complaining of a splitting headache and Joe's refusing to leave his room. Probably best he stays there. It's not like he can do anything if he gets up."

     "How's Izzy?" Andrew asked Lungelo. "First her leg, then this."

     "She says the pain's gotten worse and the wound looks red and inflamed," the other man replied. "I know what everyone's thinking but it's not the cow. Halona talked to the rover's computer, the medical expert system, and described the symptoms. It found a perfect match." He paused for dramatic effect. "It says it's Strep 14-b."

     Everyone stared in fear. "But..." began Andrew, putting a hand on the wall for support as the strength seemed to leave his legs. His headache seemed to pound harder as the news sank in. "But that's gone. They wiped it out fifty years ago."

     "After it killed a thousand people," said Philip grimly. "They had to seal off an entire level of the city and just wait for it to burn itself out."

     "But it can be cured, right?" said Susan. "Any antibiotic will cure it. It only killed so many people because it infected people faster than they could manufacture antibiotics."

     "Yes, that's right," said Andrew, nodding with relief. "We've got plenty of antibiotics in the medical supplies." He ran a shivering hand across his eyes. "God, but I was worried for a while there. I thought we were all going to die."

     "We're not cured yet," warned Philip. "Let's all get ourselves treated and congratulate ourselves when we're all better."

     Good advice, thought Andrew. He and Susan finished getting dressed and then went to where the medical supplies were stored. They found the bottle containing the precious liquid and Susan picked it up and read the label while Andrew grabbed a handful of disposable syringes. He saw Susan still staring at the bottle, frowning. "Something wrong?" he asked.

     "Look at the lid," she said, handing the bottle across. "What do you think?"

     Andrew stared at her curiously, then looked at the bottle, examining it carefully. "The seal looks broken," he said. "But just a little. As if someone's opened it carefully, trying to disturb the seal as little as possible."

     "Maybe it just got bumped while it was being handled," his wife suggested. "Or maybe someone was careless putting the lid on in the factory."

     "A machine puts the lid on," Andrew pointed out. "You're probably right, though. It got bumped or something. That's probably all it is." He raised the bottle to his eyes and examined it again, frowning unhappily. Then he went to the wall terminal and called Lungelo.

     "What can I do for you, Andy?"

     "You gave Izzy antibiotics when she hurt her leg, right?" Andrew asked him.

     "Yes, but we've still got plenty left."

     "What did it look like? The antibiotic?"

     "Look like? I don't know.... Sort of yellowish I think. Why?"

     "That's what I thought," said Andrew, frowning at the bottle again. "I looked at it before we left the city, to check we had everything we might need. I remember noticing the colour then. Now, though..." He looked across at his wife and she looked back at him, now looking truly scared.

     "What?" Prompted Lungelo.

     "The liquid in our bottle now is colourless," said Andrew flatly. "Completely clear."

     There was a pause from the intercom before Lungelo spoke again. "I'll go check our bottle," he said. "Just be a moment." Then there was silence.

     "How can we all have gotten 14-b at the same time?" asked Susan while they were waiting. "Say some spores somehow got aboard someone's rover. Someone gets infected. Even if he passes it on to everyone else very quickly, someone would have gotten ill before everyone else. Probably a full day before."

     Andrew nodded as horrible possibilities went through his throbbing head. "And it happened right after the barbecue," he said. "As if someone hoped that it would be blamed on food poisoning."

     "He couldn't possibly have known we'd find a cow," said Susan.

     "There'd have been something," said Andrew. "Sealed snacks in an old vending machine. A soda or a fruit drink. Something like that. He'd have suggested we try it..."

     "You can't think Joe did this to us!" said Susan in horror and disbelief.

     "No, of course not. Maybe it is all just an accident. Spores accidentally brought aboard, my stupid, tired eyes not seeing colours properly..."

     "You still there?" said Lungelo's voice from the speaker.

     There was a tone to his voice that scared Andrew. Please don't say it, he thought desperately. "Still here," he said, his mouth suddenly dry. "What do you think?"

     "It's visibly clearer," the other man said. "Also, there's more of it. The bottle was only three quarters full after we treated Izzy, but now it's full. Someone's thrown away our antibiotics and replaced it with water. Looks like we've got a remainer among us, and he's killed us all."

     Andrew couldn't bear to look at his wife. He thought he might collapse in despair if he saw the terror that he knew would be on her face. "How long have we got?" he managed to say.

     It was Susan who answered, though. "Three days," she said, her voice shaking and broken. "Maybe four. The kids..." She sobbed, and when Andrew looked at her he saw tears leaking from her eyes. It was a moment before she could bring herself to speak again. "The children somewhat less."

     "Three days?" said a voice behind them. Andrew and Susan spun around to see Jasmine standing there. She was wearing three coveralls and was still shivering.

     "It's probably not 14-b," said Andrew reassuringly, going over and putting his hands on her shoulders. "It just matches the symptoms, that's all. There're are thousands of Strep bacteria. We probably brought something back from the dig. Something that our bodies'll manage to fight off of their own."

     "You think?" she said, staring up into his his eyes desperately.

     "I'm sure of it," said Andrew, pulling her in for a hug. "Go back to bed now and get under the covers. Keep warm and get plenty of fluids."

     "I can help the others," she insisted.

     "They'll be fine," said Susan, taking her from Andrew and hugging her. Then she held the girl at arms length. "We'll all be fine, I promise."

     "Doesn't this mean we'll be going back to the city? Back to New London?"

     "We're still considering our options," Susan told her. "Now get back to bed."

     Jasmine nodded and went back to the ladder which she climbed with an awkwardness that testified to the ache in her limbs.

     "It is 14-b, though," said Andrew. "Someone tampered with the antibiotics. They wouldn't have taken a risk like that unless they were going to give us a seriously bad disease."

     The very suggestion made them freeze in horror. The Strep outbreak was still spoken of in hushed voices back in New London. Level eighteen, named Crouch End, was still uninhabited fifty years later. No-one wanted to live on the level in which so many people had died, every exit held by armed guards ordered to shoot anyone who tried to leave. Maintenance workers and inspectors spoke of ghosts lurking in the darkness and those who used the stairs between levels seventeen and nineteen hurried past the sealed off exits in between as if some unseen evil might still reach out to infect them. The idea that the microbe responsible might now be aboard their rovers was too terrible to even contemplate, but the conclusion was almost inescapable.

     "The remainers have always tried to avoid taking lives in the past," said Susan. "Maybe it's a less dangerous bug. Maybe they're just trying to scare us back to the city." She stared hopefully at her husband, her eyes begging him to confirm it.

     "Maybe," Andrew admitted, not wanting to deny her even such a slim hope. "If so, though, they've made a mistake. We've got cameras now, continuously recording the airlocks and the cockpits. We can see who came aboard and tampered with the antibiotics."

     He led the way to the cockpit and called up the recordings. "Rover," he said. "Use facial recognition to identify everyone passing through the airlock since we left New London."

     "Working," the autopilot replied. "Five persons identified. Andrew Birch, Susan Birch..."

     "Yes, yes," said Andrew impatiently. "Who else? Who apart from members of our family?"

     "No other persons have used the airlock since we left New London," the autopilot replied.

     Andrew and Susan stared at each other. "Perhaps the antibiotics were tampered with before we left the city," said Susan. Her tone of voice told Andrew that she didn't believe it.

     "If one of Lungelo's family's the remainer," Andrew said, "he might have tampered with our antibiotics, and Philip's, before we set out and left his own just in case, which is how he was able to treat Izzy."

     "Lungelo looked sick just now," said Susan. "The remainer wouldn't have given himself a deadly disease, would he?"

     "He might if it is indeed a less dangerous disease," Andrew replied. "Something that looks like 14-b but isn't. God but I hope so! How long do antibiotics last? Could we find some here, at LaSalle, do you think? They'd have had an infirmary surely."

     "Would it still be any good after two hundred years?"

     "It would be frozen. That would preserve it, right? Like the cow." He looked thoughtful for a moment, but then he shook his head regretfully. "It took us a week to uncover the research facility. The infirmary will be smaller, but we're still talking about a couple of days to remove the ice it's buried under, and then we might find that everything in it was destroyed before The Freeze. If we've only got three days, we can't waste most of it on such a long shot."

     "Then our lives depend on the remainer having given us some lesser bug rather than Strep 14-b," said Susan, sitting back in the co-pilot's chair. She pressed the palms of her hands to her eyes as if to rub away the mental image of what lay ahead. "So what do we do? Sit here and wait to see if we die? Hurry back to New London, hoping it takes longer than a week for us to die?" She shook her head. "No, that doesn't make sense. Even if we go running back to the city it won't stop The Return. There'll still be time for another expedition to get out here and finish what we started. The only way this stops The Return is if months go by before New London realises there's anything wrong. This only stops The Return if we all die out here." She stared at Andrew. "Which means it is 14-b. This only works for the remainer if we all die."

     "There is one thing we could do," said Andrew though. "There's one place we might be able to get some antibiotics, less than a day's drive away."

     "What's that?" asked Susan, looking at him hopefully.

     "New Philadelphia."