The Village station, 13 March, start of third guard shift, midnight

The milestone marked the sixth mile from Chiusi and Mustela turned to enter the courtyard of the mansio.He tethered his horse, walked up the stairs to his room, opened the door and closed it behind him. He was exhausted. He raised the wick on the oil lamp that was about to go out.

‘Hello there,’ said a voice in the dark.

Mustela drew his sword.

‘I guess my time hadn’t come yet,’ said Publius Sextius. ‘Surprised, my friend? Dead men don’t show up out of nowhere, do they? But as you can see, I’m not. You thought you could take your time since I was out of the picture and so I made it here first.’

Mustela lunged forward, but Publius Sextius was ready for him. He parried the blow with his gladiusand with a quick thrust sent the weapon flying from his attacker’s hand. He then pounded his cane flat against Mustela’s chest. The man collapsed to the ground.

Publius Sextius jerked him up and sat him down on the only chair in the room. Leaning back awkwardly, he seemed a disjointed puppet.

‘Let’s start by you telling me what signal you sent,’ he hissed into his face.

‘Forget it.’

Publius landed a stone-hard punch in the middle of his face and Mustela whimpered in pain.

‘You’ll kill me anyway, so why should I tell you anything?’

‘You’re wrong. If you talk I give you my word of honour I will not spill your blood.’

Mustela, still in pain from the wounds incurred during his long journey, was destroyed in body and spirit.

‘They say that Publius Sextius always keeps his word,’ he managed to get out.

‘And so be it, in the name of the gods,’ replied Publius Sextius. ‘Well, then?’ he said, raising his cane again.

‘The message was to intercept two speculatoreson the Via Flaminia or Cassia.’

‘I see,’ replied Publius Sextius, receiving the news with seeming indifference. He moved behind Mustela. ‘Anything else?’

‘Nothing else, I swear it. I’m a wreck. I can’t take this. Leave me in peace.’

Publius grabbed his head and twisted it with a swift wrench, breaking the man’s neck.

‘There you go. You’re at peace now and I’ve kept my word.’

He went down to the courtyard, mounted his horse and set off at a gallop.

In Monte Appennino, Lux Insomnis, pridie Id. Mart., tertia vigilia

The Apennine Mountains, Never-Sleeping Light, 14 March, third guard shift, one a.m.

Publius Sextius had assumed control of the signalling station manu militari.He had taken command of the squad of signal corps auxiliaries by showing them his titulusand the persuasive, knotty symbol of his rank. He went straight to the signalling tower to transmit the counter-order and save the lives of Rufus and Vibius, whom he didn’t know but who, he was sure, were two courageous young servants of the state. Lighting the fire for the beacon was difficult enough in itself. The weather had worsened considerably. Clouds covered the moon and lightning bolts were discharging their flames on the mountain peaks, swept by a raging wind. It had started raining again, on and off. Publius Sextius was gripped by mounting distress, obsessed by the realization that time was slipping away. His mind continued to calculate the distance he might have been covering if he had not been forced to interrupt his onward journey. But how could he go on without trying to protect the other messengers? The only way to stop them from being killed was using the light, Lux Insomnis,like the code name of the station. But when he was finally able to transmit the message, no one answered.

‘Answer me, you drunk bastards, answer me,’ growled Publius Sextius, teeth clenched, but no light shone back over the Apennines, apart from the bluish flashes of lightning.

He left the signalling tower and went down to the room below, spreading the map that Nebula had given him out on the table. He placed a lamp on the map and ran his finger along the route to the point at which it intersected with the Via Cassia.

‘Too far,’ he murmured. ‘Too far off my road. I would never make it in time. May fortune assist you, lads.’

He walked out to where his horse was waiting and rode off.

In truth they had received his signals up at the station, but could do nothing but remain inside the building because the storm was lashing the post with unnatural force. Clouds heavy with hail, edged in white, shot through with flashes and bolts of lightning, were unleashing a torrent of freezing rain on the signalling tower. Clumps of ice exploded upon impact with the stone paving slabs, shattering into thousands of pieces that glittered like diamonds in the sudden bursts of light. The whole building resounded with the incessant clatter, as if it were being targeted by a thousand catapults.

They could see the signals from the small splayed windows of the tower and the station master wondered what on earth could be happening in Rome, for such contradictory messages to be arriving in such quick succession. But the long wake of the civil wars had taught him not to ask too many questions and to follow orders as long as the accompanying code was exact. This new message was to annul instructions to intercept two speculatoresand was to be put into effect immediately. The original message had been an order to kill, and the chief realized that he’d have to send a man out to stop it before it reached its destination. Hardly a man, in reality. The only person he could send was a boy — skinny, almost skeletal, with a perpetually bewildered expression. He had not the faintest hint of a beard, but a light downy fuzz like a chick’s. That’s why he was called Pullus.

He had neither father nor mother — or rather, he did, like anyone else, but no one knew who they were. He’d been raised by the army and was happy to do anything he could to make himself useful. He’d been a stable boy, baker, cook, dishwasher. But what he did really well was run. He could run for entire days and nights, light as a feather, animated by an energy that came out of nowhere. He couldn’t run for as long as a horse, but when it came to getting around on steep, rocky terrain, Pullus was second to none, man or beast. He climbed like a goat, scaled mountain slopes like an antelope and leapt from one cliff to another with an agility and grace that contrasted greatly with his frail, ungainly appearance.

The station master handed him a ciphered document with his seal and ordered him never to stop until he succeeded in intercepting the original message. His chances were good, as he would be aided by the bad weather and by his unequalled familiarity with every nook and cranny of the territory, which would allow him to shorten and simplify each leg of the journey.

Pullus left at once, in the rain and hail, holding his shield over his head. The onslaught that was hammering away at his lid stopped before long and he was able to rid himself of the extra weight. Hiding the shield behind a bush, he ran on unhindered at even a faster clip.

Pullus never hesitated or paused. He ran down rain-flooded paths, raising splashes of water that soaked him to the neck. He ran through the barren fields, under the leafless trees, through the sleepy villages. Dogs barked at the approach of his swift, light stride, taking him for the king of thieves, but they soon fell silent as his footfalls faded into the same nothingness they had materialized from.

He pondered his mission as he raced on, the young, tireless runner. Could he save both of them? If he had to choose, one would have to die so the other could be saved, but which one? He thought mostly about who the speculatoresmight actually be, and after discarding a few hypotheses, he was down to two names, the most probable. Two faces, two voices, two friends among the very few that he had. Including the dog at the station and the goat that he milked every morning.