Windsor's shoulders had been protected by the life support machinery that the surface suits contained high up on their backs, but his hips and buttocks had been left red and blistered by the cold. He had to administer the thermal cream to himself because Andrew was too busy looking after Fox and Cheval.

     Cheval had been hit in the leg, just above the knee. The bullet had gone right through, though, without hitting either the bone or any major blood vessels and needed only a bandage until they got him back to the city. He tied it as quickly as he could and then, despite all Andrew's protestations, he hobbled out to the cockpit to supervise the rover's continued pursuit of Fox's rover.

     Fox's injury was more serious. His lung had indeed collapsed and, on top of that, a medium sized vein had been cut in two. With the living room turned into a makeshift infirmary, bloodstained bedsheets draped over every piece of furniture, Andrew had used the rover's small and rather basic ultrasound machine and a laparoscopic waldo to insert a clamp to stop the bleeding, under the direction of a doctor watching and talking to him over a video link. Andrew had then patched the injury so he could re-inflate the lung. Hopefully, that would keep him alive until they could get him to a hospital.

     Once he'd sorted them out as well as he could Andrew went back to Windsor, who was sitting backwards on an armchair, still rubbing the salve onto his blistered skin, wincing with pain. "That looks bad," he said sympathetically.

     "Feels bad," Windsor replied through gritted teeth. "We've all had the seminars, of course. They're supposed to tell you what to expect, but they don't. It hurts really bad."

     "Is the cream working?"

     "Does it feel warm?"

     Andrew touched the side of Windsor's hip with the tips of his fingers, trying not to disturb the cream smeared on it. "Yeah. Like a lukewarm cup of tea." Chemical reactions in the cream as it reacted with the air were releasing heat. It would continue to do so for about half an hour, by which time his skin and the flesh beneath should have been re-warmed to body temperature. "Doesn't look too bad, actually," he said. "Maybe the skin will survive. You might not need skin grafts."

     "That would be nice," said the Constable. He looked across at Fox, who'd been tied down to the sofa with strips of cloth cut from a bedsheet. "Wish I'd been the one to shoot him."

     The Historian opened his eyes a crack and turned his head to look at him. "I always hoped..." He paused whilst he gathered his strength to speak again. "I always hoped I could do what I needed to do without hurting anyone," he managed to say.

     "One man dead," said Windsor flatly. "Two more injured. It could have been three men dead."

     "Kartoshka acted from his own convictions. He persuaded me as much as I persuaded him."

     "And Lavandel? The guy who sabotaged rovers seventeen and eighteen? Did he persuade you as well?"

     "There are many of us who feel that leaving the Earth would be a suicidal mistake. Too many for you to stop us all. I may already have succeeded. My rover has too much of a lead over this one. You can't catch it in time."

     "How many of you are there?" asked Windsor. "Give me their names."

     "I don't know any names. I didn't know it was Lavendel aboard rover eighteen. Kartoshka was the only one whose name I knew."

     "Do you have a leader? Who gives you your orders?"

     "We don't have a leader. Just a bunch of people all driven by their own sense of morality."

     "I don't believe you. You will tell us what we want to know..."

     "Frank," said Andrew, putting a hand on his arm. "He's in no condition to talk right now. He needs to rest. I did my best to patch him up but I'm no doctor. He needs a real doctor who can perform a real examination. He won't tell you anything if he dies before we get him back."

     Windsor nodded reluctantly and settled face down on the armchair, his blistered back seeming to turn redder even as Andrew watched. The Constable said nothing, but Andrew could see the expression on his face that told him he was in pain. He needed to rest as well, Andrew decided. Probably best to leave them both to get a bit of sleep.

     He tested Fox's bonds to make sure he couldn't slip free, although the condition he was in, he would probably have died if he tried. Then Andrew quietly left the room and went up to the cockpit. He found Cheval sitting in the pilot's seat, studying the tracks left by Fox's rover ahead of them. To look at him, there was no visible clue that he'd been injured. Only the slight bulge around his right leg where his coveralls hid the bandages.

     "There was a crevasse a few metres behind where Fox was hiding," he said conversationally as Andrew took the seat beside him. "If we'd tried to reverse past Fox, we'd have gone right into it. That's what he was hoping for. And I would probably have done it if you hadn't talked me out of it."

     "You didn't need much convincing," Andrew replied. "You knew it was a bad idea even as you said it." Cheval grunted his gratitude. "Any way of telling how far behind we are now?" asked Andrew.

     "No," Cheval replied. "There isn't a satellite due to pass over this area for two days. It'll probably be close, though. He'll have told his rover to make full speed no matter the terrain it's driving over. A risky tactic. It may come to grief along the way, but that's what I would have done."

     "And if we do catch it up, we've got to stop it," said Andrew. "How do we do that? Did you bring any weapons large enough to stop a rover?"

     "No," said Cheval, still staring out through the cracked window. "We did not."

     "So what do we do?" repeated Andrew.

     "I'm working on it," said the Sergeant, who then refused to say anything else. Andrew sighed and went back to the living room to keep an eye on Windsor and Fox.

☆☆☆

     Cheval hardly left the cockpit during the next three hours, leaving only when a call of nature grew too demanding and returning with hands still wet from the wash basin. Andrew brought him a cup of tea and a few snacks at the end of the second hour, which he ignored. Ahead of them, Etna Mons grew on the horizon. A vast cone of rock and ash shining in the pale light of the distant sun and silhouetted against the splendour of the Milky Way. Cheval stared at it as if it had murdered his family.

     The rover's autopilot wanted to take them by a safe route that avoided most of the steep slopes and patches of bare rock but Cheval overrode it and took them by the direct route. As a result the rover soon found itself halfway up the side of a steep valley, forcing the two men to cling to the arms of their seats as the vehicle tilted more and more to the right. Now and again it lurched alarmingly as the wheel cleats struggled to get a grip on the rock.

     "Are you sure this is a good idea?" said Andrew with increasing fear. "We're right at the maximum tilt. We're going to overturn!"

     "If Fox's rover also wants to take the safe route, this is our last chance to catch it," said Cheval. He grinned across at Andrew. "Don't worry. They always give it a safe margin for error. We may have ten degrees more than they claim."

     "I hope we don't have to put it to the test."

     Andrew went back to check on Fox and Windsor but came running back when he heard the Sergeant gave a loud cry of triumph. He arrived to see him pointing at the monitor screen showing the feed from the infra-red camera. There was a bright spot of yellow climbing one of the last ridges between them and the mountain, no more than a couple of kilometres ahead of them.

     "There it is!" cried Cheval, still pointing. "We're still gaining on him. Looks like we'll catch up before it gets to the summit."

     "And then what?" said Andrew. He looked out the window to see if the other rover was visible to the naked eye and saw what appeared to be snow falling, although it fell like chips of gravel in the vacuum. Vapour from the volcano, he realised. Shot into the sky by the roiling, bubbling lava in the caldera and then condensing into tiny flecks of silicate crystal. It would probably have covered the tracks of Fox's rover if they were still following them. Hiding them from sight. It was lucky that Fox's destination was so close ahead of them or they might have lost him here.

     He realised that Cheval hadn't answered his question. "And then what?" he repeated. "We draw up alongside the other rover, and then what?"

     "I have an idea," the Sergeant replied.

     Andrew waited for him to elaborate, but the Sergeant remained silent. "What idea?" Andrew prompted him. "If you're thinking of using this rover to overturn the other one, I don't think it'll work. Not unless you're really lucky." Still no reply. "And if you're thinking of getting ahead of it and blocking its path, you're likely to end up with both vehicles in the caldera. You might slow it to a crawl but it'll be able to push us..."

     "I'm hurt," Cheval interrupted him. "Windsor's in even worse condition. It would be up to you."

     "What would?" said Andrew with growing apprehension.

     "To jump over to the other rover and stop it."

     Andrew stared at him. "You mean, while both rovers are still moving?"

     "Yes,"

     "Jump across the gap between two moving rovers? If I fall, I'll be crushed by the wheels."

     "You won't fall. You can grab hold of the radiator fins."

     "They're hot."

     "The insulation in your suit will protect you from heat as well as cold. You can do it, if I can bring this rover alongside that one."

     "You're mad!"

     Cheval looked across at him. There was utter determination on his face. "If I could do it, I would. This is our last chance to save the dysprosium. If we fail, Fox wins."

     "So let him win. There's not enough at stake to be worth risking my life for. If we fail, then what? The human race gets to spend millions of years safe and healthy on this planet."

     "If we fail, we lose the sun. We lose the galaxy."

     "Colonising the galaxy was always a fool's dream. The distances are too great."

     "If we can return to the inner solar system, we can colonise the galaxy. We can already survive a hundred year space voyage in suspended animation. With the power of the sun behind us, we'll be able to cross several light years in a hundred years. All it needs is for you to get your ass out there and make the jump. The future of the human race depends on one man having the balls to try, and you're the only one here who can do it."

     Cheval stared at Andrew and Andrew looked away uncomfortably. He felt the other man's eyes on the side of his head. He could refuse, he knew. Cheval couldn't force him. A lawful order didn't include making him risk his life. He wanted to do it, of course. He wanted to be the one who saved The Return. He wanted to be a hero. Wanted his wife and children to look at him with pride and adoration, but he knew, as sure as ice is cold, that when the time came and he was standing on top of the rover with the leap ahead of him, that he wouldn't be able to do it. His legs would freeze up. The sight of the wide gap and the deep drop with the cleated wheels waiting to crush him and shred his body to pieces would paralyse him and leave him able to do nothing but climb back down to the airlock in shame and defeat.

     He was too much of a coward to do it, he knew, but he was also too much of a coward to say no to Cheval, so when the Sergeant asked again he nodded silently. "I'll try," he said. "I'll try."

     He saw the doubt in the other man's eyes, but the Sergeant nodded nonetheless. Andrew settled back in his seat and closed his eyes, praying to any gods that might be listening that they weren't able to catch up with the other rover in time.