Trundling across the frozen surface of the Earth at around twenty kilometres an hour, the Birch family's hab-rover came across the tracks left by Reginald Fox's rover just under thirty minutes later.
The rover was equipped with cameras that fed what they saw directly to the sophisticated autopilot that had software designed to search for and recognise the scratches in the ice left by two metre high, steel cleated wheels. Most traffic on the surface went along well established trails that had been found to be safe. They weren't straight, though, but wound their way between possible and actual hazards and the people who had designed this latest generation of rovers, a decade before, had worried that an injured pilot, perhaps only semi-conscious and desperate to get himself or a family member to safety, might wander from the safe path and come to grief. The most used roads had transponders along them that the rovers could follow, and the exact route was programmed into their autopilots anyway so that travellers following the older, well established routes had almost no chance of getting lost, but newer roads were still nothing more but scratches in the ice. The rover's designers had therefore decided that the rover's on board AI should be able to follow a set of wheel tracks so that it could bring its human passengers home all by itself, should it ever be necessary to do so.
Andrew had activated the rover's tracking systems, therefore, although he remained in the cockpit to watch the terrain they were crossing with his own eyes, just in case the autopilot missed the signs. His fears were groundless, though. They were climbing the side of a high ridge when the autopilot beeped, snapping Andrew out of the light trance he'd begun to fall into. He jerked back to full consciousness and told the rover to stop and back up a few metres. Then he stared out through the cockpit windows at the icy ground ahead.
There it was, just a few metres in front of them. A pattern of scratches in the pristine nitrogen ice telling that a hab-rover had passed this way, crossing their path, sometime since the atmosphere had finished freezing out. There was no way of knowing how long ago, of course. It could have been twenty years ago, when the first vehicles had tentatively emerged from the underground city to see what had become of their planet, or it could have been just moments before.
There was movement behind him and Andrew turned to see his whole family crowded in the doorway behind him. "Have we found it?" asked James.
"Looks like it," Andrew replied. "Well, here we go, I suppose." He turned the rover to follow the tracks east, towards the mountains.
Susan came fully into the small room and sat in the co-pilot's chair where she stared ahead, as if she could see the lights of Reginald Fox's rover reflected from the ice further ahead. "How far ahead of us is he?" she asked.
"Phil said about five hours," Andrew replied. "Say about a hundred klicks."
"But he's picking his way carefully across unfamiliar terrain while we can make faster time across ground that he's already tested for us. We'll be catching him up."
"Even if we are, we're not going to gain that much ground any time soon."
"What if he's stopped and laid an ambush for us?"
Andrew laughed. "You mean, crouched down behind a boulder, aiming a sniper rifle at us?" He sobered quickly when he saw his wife's eyes widen with hurt and anger. "I'm sorry," he said, "but he has nothing to ambush us with. We don't carry weapons or explosives. We've got sharp knives and that's about it. No, he's going to be running, to keep ahead of us until he gets to wherever he's going. He's not going to hang around and let us catch him up."
"You don't know what he's going to do," his wife pointed out. "These rovers come equipped with all kinds of equipment. Who knows what he could rig up if he really wanted to?"
"Looks like he's heading into the mountains," said James, leaning forward across his father's chair to see the monitor screens. "I mean, right over them. Right over the highest parts."
"Can he do that?" asked Jasmine, sounding alarmed. "Right over the top of a mountain?"
"These aren't mountains like in the movies," Andrew assured her. "Not like the Himalayas. By global standards they're not much more than a high range of hills. They have flat, smooth tops. Reg told me once that, before The Freeze, people used to climb them. Just walk up them. They were lumpy and uneven in places, but there's a deep layer of water ice all over them now, smoothing them out. We should have no trouble driving over them."
"Will it be daytime by the time we get up there?" asked David hopefully. 'There should be a great view!"
"There'll be no time for sightseeing I'm afraid," said Andrew. "Everyone out now. I've got to talk to Phil, tell him we've picked up the trail of his fugitive. Where are we, James?"
"Place called Keswick," his son replied, staring at the old map. "So far as I can tell. He'll be able to get an exact satellite fix on our transponder."
Andrew nodded and told the rover to open a line to the dig site.
☆☆☆
"Looks like he's following the ridge," said James an hour or so later, looking out through the cockpit window from the co-pilot's seat. "About half way up. He's probably hoping that there'll be patches of bare rock that won't preserve signs of his passage."
Reginald Fox's rover had only climbed half way up the mountain after all. It had then turned to run parallel to the valley below, on a sheet of ice that was inclined at an angle to the horizontal. Andrew had turned their own rover to follow it.
"But that's dangerous!" said Susan from the doorway behind him, clutching hold of the door rim to keep herself steady as the rover tilted heavily to the right. "His cleats won't be able to get a grip on bare rock. His rover could slip and fall. If we follow him, we could slip and fall."
The whole family was gathered once more, drawn by the romance and allure of the chase. The posse hot on the trail of the dangerous, fugitive outlaw as if they were re-enacting one of the old westerns from the city's huge media archive. It was now the small hours of the morning but none of them thought of getting any sleep. Who knows what exciting developments they might miss?
"If he made it, we can make it," said Andrew.
"You promised you wouldn't put the children at risk."
"Reg clearly doesn't think there's a risk," Andrew replied. "If he crashes, it's over for him, and for the Remainers. We recover the dysprosium from the wreckage and The Return takes place on schedule. He's gone too far to risk that. Ended his career, earned himself a long spell in prison. If he fails to keep the dysprosium out of our hands it was all for nothing. I'm guessing that means he's confident he won't come to grief on this ridge."
"And you're willing to gamble all our lives on that?"
"Hab-rovers have very low centres of gravity. Everything heavy's under the floor. They're rated as stable on sideways tilts up to twenty eight degrees and inclinations up to forty degrees. This slope is..." He checked an instrument on the dashboard. "Nineteen degrees."
"Here it is, maybe," Susan replied, her eyes bright with anger and worry as they fixed on her husband. "What about further along? And I assume those measurements are for ice, on which cleats can get a good grip. What are the numbers on bare rock?"
"It's not bare rock..."
"It might be up ahead."
Andrew nodded. "Let's see what the map says," he said. He called up two maps. A modern radar map made by one of the terrain mapping satellites that had been launched since The Emergence and an Ordinance Survey map from before The Freeze. Both had contour lines bunched closely together at the rover's current location. Using that as a reference, he looked ahead, at the route he thought Reginald Fox was most likely to have taken.
"The mountain only extends a few klicks further," he said. "Then, if he continues east, it's the Eden glacier."
"Another glacier?" said David, sounding scared.
"This one will be solid. No geothermal heat to make it unstable, just like all the other glaciers we've crossed. After that, though, it's the Pennines. More mountains. There are plenty of safe paths through them, but if his plan is still to shake us off he'll probably avoid them and take the riskier paths instead."
"And we'll just keep on following, will we?" said Susan, staring sharply at her husband.
"There are half a dozen life hutches within a few miles of the route he'll probably be taking," said Andrew. "I can drop you and the kids off at any of them. They'll send someone to pick you up within a couple of days."
"Or we could all stop at a life hutch," his wife suggested hopefully. "The rover's fully capable of following Reg by itself."
"Not as capable," Andrew replied. "There's always a possibility something'll happen it's not equipped to handle. I have to stay with it, but you don't. You can keep the children safe until it's all over..."
"I don't like the idea of being trapped in a hutch," Susan replied, though. "Dependent on someone else to rescue us. Here, in the rover, we've got options. In a hutch, all we can do is wait and hope someone comes before the food runs out."
"The city's only a day's drive away," Andrew pointed out. "How long do you think you'll be staying there?"
"No life hutch," she replied firmly. "Not unless you're there with us."
Andrew frowned unhappily. "Well, we've got time to think about it," he said. "It'll be another twelve hours before we pass the last life hutch, assuming Reg keeps to the same course."
"And in the meantime we're following this incline," said Susan, still hanging onto the door rim as the rover swayed between almost level and a twenty degree tilt to the right. "Hoping we don't lose traction and slip sideways down the slope, maybe rolling over as we go and starting an ice slip that'll leave us buried at the bottom..."
"If he made it, we'll make it," Andrew repeated. "I wouldn't do this if I thought there was any danger to you. I promise..."
A beeping came from the instrument panel in front of him. Andrew turned to read the message that had appeared in one of the monitor screens. "The Rover's lost Reg's trail," he said, frowning.
He and Susan stared out through the cockpit window at the ground ahead. At the same time the rover began to bounce and judder as the ground it was travelling over became rough and uneven. "Shit!" said Andrew. "Rover, stop!"
The rover came to a halt, still leaning at a steep angle to the right, and the children crowded forward to see what their parents had seen. Ahead of them, the ice was missing and the rock and soil of the land's original surface was exposed; lumpy with boulders and narrow crags and glistening brilliantly in the rover's headlights where shards of ice still remained in hollows and crevices.
"Ice slip," said Andrew. "The weight of Reg's rover caused the ice to give way under him." He turned on the rover's spotlight and aimed it to the right. The ice missing from the hillside lay in a wide, untidy spreawl further down the mountainslope, brilliantly white except where it was stained by soil and dead, frozen vegetation. There was no sign of Reginald Fox's rover, but at that angle and distance the spotlight wasn't able to illuminate the area very well. "The rover could be buried under the ice," he said.
"Or it might be a crumpled wreck where it rolled further down the mountainslope," suggested Susan. "I told you this wasn't safe."
Andrew sat in thought for a moment. "I'll suit up," he said at last, rising from his seat. "Go take a look. James, you wanna come with me?"
"Andy, no!" cried Susan in fear. "Reg might be out there! He might attack you!"
"Why would he attack me?"
"To take our rover. If his is wrecked..."
"He might be trapped in his rover," Andrew pointed out. "He might need rescuing."
"It's too dangerous!"
"I have to do this. You know that."
Susan stared at him, her eyes pleading, but then she nodded. "Okay, but I'm coming with you," she said. "We don't put the children at risk."
"I'm stronger than you, mum," James pointed out with a smile. "If Reg attacks us, I've got a better chance fighting him off than you would have."
"You're only fourteen years old!" his mother replied anxiously. "You're only a child."
"Maybe," said James, still smiling, "but I'm still stronger than you are. Wanna arm wrestle to find out?" He lifted a hand to her challengingly.
"He's right, Sue," said Andrew earnestly, "but he won't be going anywhere near Reg's rover. He's only coming in case I twist an ankle on a rock or something. Block the inner airlock door from closing, just in case Reg's out there on foot and tries to get on board. The safeguards won't let the outer door open unless the inner door's closed." Susan nodded reluctantly.
"Okay, James," said Andrew. "Let's go get suited up."
Susan and Jasmine took their places in the two cockpit seats as Andrew and James squeezed past David, heading for the outfitting room.
☆☆☆
It was the first time Andrew had emerged from a hab-rover that wasn't parked on level ground.
Descending the ladder, which sloped so that he was almost hanging beneath it, was tricky, but he made it and waited at the bottom for his son to join him. In the meantime, he examined the wheels and the ground the rover was standing on. The giant, steel cleats of the wheels, each a full two centimetre thickness of triangular steel, hadn't been bent or blunted by the bare rock, he was relieved to see, but they were in contact with the ground only on their pointed tips, meaning that they weren't getting much of a grip. The rover had actually slipped sideways a little, he saw, scraping grooves in the rock until one of the cleats had come up against a rounded nob of rock that prevented it from slipping any further. He cursed under his breath. The rovers had been designed to drive over ice. If they had to travel any distance over bare rock, they could have problems, especially if it was on a slope. He began to wonder whether he should have listened to his wife's warnings. Had he put them all in danger by following Reginald Fox here?
James, meanwhile, had reached the bottom of the ladder and dropped nimbly to the ground. He dropped the way he always had, trusting the cleats of his boots to get a grip on ice, but instead they skidded on the bare rock and he slipped and fell with a muffled oath. Andrew ran over to help him, but the boy was already picking himself back up, patting the side of his body where it had been partially numbed by the momentary contact with the cold rock.
"Are you okay?" asked Andrew. "Go back in and check yourself out."
"I'm fine," James replied.
"It only takes a moment to get frostbite."
"I haven't got frostbite. I'm okay." He emphasised the point by moving away from the rover, carefully picking his way down the uneven slope to the sprawl of ice a couple of hundred metres below. Andrew cursed under his breath again and followed him.
Father and son carefully made their way down the slope, across ice that had been scraped into furrows and gulleys by the slide from above. As they approached the mounded sprawl of ice, though, it became increasingly easier to see that Reginald Fox's rover was not in it. It simply wasn't deep enough to contain such a large vehicle, unless it happened to cover a large pit in the ground. The matter was settled when they finally reached the mound and saw an opening in the eastern side where a large object had pushed its way free leaving two ridges of pulverised ice alongside the telltale tracks of a hab-rover's wheels.
"By some miracle his rover didn't tip over," said Andrew, wandering around, examining the site. "He landed upright and was able to simply drive away."
"But we might not be so lucky if the same thing happens to us," said Susan over the intercom.
"You're right," said Andrew. "We don't go any further. Not while you guys are aboard. When the bus from the city gets here, they can come aboard and you can take the bus back to New London."
"And you too," said Susan insistently.
"No, I'm staying here," said Andrew, though. "I'm going with them, after Reg. I know this rover, all its foibles and eccentricities. I can help them catch up with him."
"You can tell them anything they need to know over the radio."
"We may not always be in radio contact with the city. He might have rigged something up to jam communications. Think of all the repairs and modifications we've made over the past five years. The atomic generator shielding, the autopilot... Think how we'd feel if something happened to them because they didn't know that the oxygen recyclers get their power from the drive systems and not the general habitation systems."
"It's all documented. Everything we've done to the rover is in the log."
"The time it takes to look something up in the log might make the difference between life and death. I've got the knowledge instantly on hand, in my head. I have to be here, Sue. You know that. I'm sorry but I have to be here."
"Then I'm staying as well."
"The children need you, Sue."
"We're hardly children any more, dad," protested James. He had picked up a piece of frozen vegetation and was examining it curiously, but now he dropped it to give his father his full attention. "We'll be fine in the city without either of you."
"I want your mother safe just as much as you," Andrew replied, putting a hand on his shoulder.
"Because you know it's dangerous!" said Susan triumphantly.
Andrew sighed. "Yes, it's dangerous," he admitted. "But you know what's at stake. Nothing less than the future of the human race. Whether we stay here on Earth or return to the inner solar system. That's why it's a risk worth taking, but I'm the only one who needs to take the risk. You know that, Sue. So do you, Jim, and the rest of you."
There was a moment of silence as Susan digested the fact. "Doesn't mean I have to like it," she said at last."
"No-one's asking you to like it, Sue," said Andrew softly.
There was nothing more from Susan. Andrew waited a minute or two to make sure she'd given up the argument, then began heading back to the rover. "Come on, Jim," he said. "Let's get back inside."