They set off across the snow accompanied by two legionaries carrying brass horns. They had gone a short distance when the air was split by three shrill blasts of the horns, repeated at intervals of twenty paces to give clear warning of their approach. Festus had explained this was the procedure followed when the general of an army wished to open negotiations with his opposite number. It was important that those sent forward to speak on behalf of the general were not taken for scouts, attempting to infiltrate the enemy’s lines. Marcus flinched at the first sound of the horns, but kept his attention fixed on the cliffs ahead. There was still no movement and the only sound beside the flat blasts of the horns was the soft crunch of snow beneath their boots.

‘Where are they?’ Festus muttered. ‘Should have shown themselves by now ... If you’re trying to pull the wool over Caesar’s eyes, boy, you know what’ll happen to you.’

Marcus tried not to think about the appalling fate that Caesar had promised him should the camp prove to be abandoned. He swallowed nervously and continued trudging forward across the open ground towards the cliff.

‘Are you sure there’s a gap in the rocks?’ asked Festus. ‘I can’t see a thing.’

‘Trust me, it’s there.’

In a blur of motion an arrow shot out from the rocks and struck the snow with a soft thud, a few feet in front of the small party approaching. They stopped and looked at the shaft quivering before them, dark against the snow. Then Festus cupped a hand to his mouth and called out.

‘Show yourselves! We have come to speak with Brixus!’

There was a brief pause before Marcus saw a figure emerge from the rocks at the foot of the cliff. He recognized him at once. ‘Mandracus.’

‘You know him?’ Festus spoke softly.

‘Yes, he’s Brixus’s second in command.’

‘Stay where you are, Romans!’ Mandracus shouted. ‘Take one step closer and I’ll have you filled with arrows! What do you want?’

‘To negotiate,’ Festus replied. ‘I speak for Caesar.’

Mandracus was still for a moment, then half turned towards the rocks as if conferring with someone hidden from view. Then he nodded and cautiously made his way across the open ground, stopping twenty paces away. He glanced over the men and fixed his gaze on Marcus.

‘Caesar’s little spy got away after all. So you betrayed us.’

Marcus felt his heart skip a beat. It was madness to be here. Mandracus might reveal the truth about his father’s identity at any moment.

‘I led the Romans here, yes,’ Marcus replied.