Outside, the fort was still and quiet and only the cool breeze brushed between the buildings. The sky was mostly clear and sprinkled with stars. A waxing moon was dimly visible behind a bank of ghostly silver cloud but would not provide much illumination for a while yet. Cato paused to listen briefly but there was no sound of the alarm being raised, and no sound of anything ominous from outside the fort. He allowed his spirits to rise for a moment as he led the other two officers towards the main gate that gave out on to the slope sweeping down towards the parade ground in the valley. He made himself walk at an unhurried pace in order to appear as cool-headed as possible in front of the Thracian. As they reached the gate they heard Severus issuing orders in a muted tone and the dull thud of boots as the legionaries hurried from their barrack block and made for their stations on the wall. The gatehouse was a timber and turf construction and a small brazier a short distance from the watchroom provided warmth and illumination for those on duty. The officers entered the gatehouse and climbed the ladder that gave out on to the platform above the gate. Stout pine posts formed the breastwork and the sentry on duty turned towards the officers and stood to attention, grounding his javelin.

‘You’re the one who reported movement?’ Cato asked brusquely.

‘Yes, sir.’

‘Make your report then.’

The sentry nodded and turned back to the breastwork and leaned his javelin against his shoulder as he gestured into the darkness beyond the defensive ditch. ‘Down there, sir. I heard voices in the direction of the parade ground, and I saw someone moving.’

‘You saw someone? You’re sure of that?’

The sentry hesitated a moment and then committed himself. ‘Yes, sir. It was definitely a man, crouched in the grass a short distance beyond the ditch.’

Quertus gave a dismissive snort as he leaned on the wooden rail running along the top of the breastwork and stared into the darkness. ‘I can’t see or hear anything . . . How long ago was it when you think you saw something?’

‘Just before I told the optio, sir.’

‘And nothing since then?’

‘No, sir,’ the legionary admitted.

Quertus tutted and turned to Cato. In the faint loom of the starlight Cato could see the sneer on the Thracian’s face. ‘Seems like I was right, after all . . . sir.’

Cato did not respond but stepped up to the breastwork and strained his eyes and ears as he stared down towards the parade ground. Beyond the ditch the ground seemed to merge into a dark mass; he could only just make out the dim outlines of the haystacks and only because he knew they were there. Macro stepped up beside him and was silent for a moment as he, too, searched for signs of danger.

‘What do you think, sir?’