How very interesting, thought Tack, knowing that to voice such a thought would probably result in him getting a beating. He looked around and instantly realized that he was in no place that he knew, for in his lifetime he had never seen a landscape completely untouched by the works of man. Perhaps there had been such places in those portions of the Antarctic still not inhabited in his own era, but someone like himself did not get to travel there—his business usually involving very close contact with other human life, however briefly, not the shunning of it.

Traveller paused for a second to kick at a pile of dung before moving on. ‘Mammoth, probably. I brought us down in an interglacial period, so they’ve moved up while the ice sheet retreated. Some big animals around in this time—we definitely don’t want to run into any of the predators.’

Tack noted the massive footprints in the snow, and suddenly it felt as if a huge emotional backlog had caught up with him. That the girl had dragged him back in time he had figured with stolid logic—which was understandable since U-gov programmed its killers for dispassion. Now he experienced a surge of emotion that flipped his stomach over and made the world grow vast around him. Mammoth, he remembered from his early schooling. Smilodons … As they walked, he turned away from Traveller to scrub tears from his eyes. Then, his voice catching, he brought the subject back to their immediate circumstances, ‘Is that mantisal thing alive?’

Without looking round, Traveller said, ‘It is alive in the only way that matters.’

‘I don’t understand…’

‘Vorpal energy,’ Traveller stated succinctly and by the man’s mien Tack knew that to push him further might result in renewed violence.

More advanced, maybe, but certainly more bad tempered, thought Tack.

However, when Traveller now glanced round, his expression changed utterly. Tack registered frowning surprise in the man’s face, then a hint of amusement. Traveller explained further, ‘Only life can travel in time and time travel is only possible in the time life exists. It is a self-fulfilling prophecy. Reality is patterned in circles, spheres, convolute and twisting dimensions. It is not required to be amenable to your logic. The linear mind finds this difficult to grasp.’

Tack felt the urge to make some sarcastic quip, but quickly repressed it.

Traveller added, ‘The limit, for life, of travel into the past is the Nodus. It is that point in the Precambrian when multi-cellular life first evolved.’

‘Why is multi-cellular life the limit? Why not single cells?’ asked Tack and waited, half-expecting to have his nose set bleeding again.

‘Ah, a sign of intelligence at last.’

Tack couldn’t help but breathe a sigh of relief.

Traveller went on, ‘That point is much debated. The energy gradient steepens into those aeons, and time travel is possible but unfeasible. The answer is connected with the quantity of living matter extant on Earth, and the amount of vorpal energy that generates.’

Something dubious in that explanation, thought Tack. ‘I do not know what vorpal energy is,’ he said.

It seemed Traveller did not attack him when he asked questions, no matter how they were posed. The first beating must have been only to disable him for capture, and the second time he was struck was because of his voicing sarcasm.

‘I could give you the equations, but you do not have the weight of knowledge to absorb them. It is just a kind of energy generated by the slow interaction of complex molecules. It was discovered some hundreds of years after your time when separate sciences were beginning to meld together.’

Tack surprised himself by beginning to understand. He had forgotten nothing of their discussion in the barn and now a picture was building in his mind. He had a vision of time sprouting from that point called the Nodus, branching and multiplying between facing mirrors of probability, expanding from one point towards infinity. This vision carried emotional weight and it frightened him.

As they finally reached the forest, it became evident that, behind the clouds, the sun was setting. Here, once they had pushed a little way in, they found the ground thick with pine needles and dead wood, and only sparsely scattered with snow.

‘Here. You may take off that pack now.’

It was dark under the trees and Tack was very tired. His training and his superb physical condition had carried him this far, but even he could not sustain indefinitely the kind of punishment he had received over the last—he glanced at his watch — twenty-five hours.

‘We light a fire now, eat and rest. You will take the first watch for three of your standard hours, but understand that there are only beasts here, so it is likely that the most that will be required of you is that you keep the fire going. You understand?’

In this forest glade, sheltered from an icy wind that propelled flecks of snow as from a grit blaster, they built a cairn of wood, which Traveller lit with a weapon only briefly revealed to Tack. The gun itself looked quite silly and ineffectual, but focused enough energy in that instant to incinerate half of the woodpile and send a huge cloud of white smoke ascending into the trees. The two of them then piled on more fuel and huddled close around the blaze.

Polly opened gritty eyes, but her vision was blurred and it took a moment for her to discern Frank standing over her. She sat up slowly and looked around. She found herself on a bed in cramped sleeping quarters, with a blanket thrown over her.

‘There a toilet?’ she asked muzzily.

Frank stepped back as she sat up and put her legs over the side of the bunk. ‘Back there.’ He gestured to the door behind him. ‘But, first, I found these for you.’

He placed a bundle on the bed: army fatigues, a small pair of boots and a couple of pairs of thick socks because the boots most certainly would not be small enough. She accepted these gratefully, then stood and walked unsteadily to the door. Following her, he directed her down a short partitioned corridor to another door. Once inside she locked herself in, took off the coat, and found blessed relief on the toilet while she took off her hip bag and checked its contents. Luckily the waterproof lining was intact, the seal-strip had remained closed, and the inside was dry. She checked the contents and was not sure what she was most glad to find, her hairbrush, rolling tobacco or her taser. At the sink she cleaned herself up as best she could, brushed her hair and applied a little make-up. Then she pulled on the fatigues, up underneath her pelmet so it held them in place like a cummerbund, then pulled on the socks and boots. Thus fortified, she rolled a cigarette and put on the coat before stepping outside again. Frank was waiting for her, glancing impatiently at his watch.

‘The sun’s near up and it’s time we got back to shore,’ he told her.

Outside, in morning light, Polly observed the navy personnel starting about their business on the fort’s superstructure. Frank led her around the side, down a short ladder to the same door through which they had entered. Soon they were down on the jetty and into the boat and pulling away, Dave and Toby greeting her cheerfully.

Suddenly she was feeling very good—full of energy and anxious to be… somewhere. Turning to look back at the fort as they pulled away from it, she now had a perfect view of the structure, with its waves of camouflage paint undulating across the stocky pillars that supported it, with its radar tower and the guns.

Impressive, isn’t it?

In her head, Polly replied, ‘Yes, I never knew about things like this.’

Do you know anything about this war they’re fighting?

‘You can read my thoughts?’ she subvocalized.