And this was a big day for these soldiers, a chance to break up the lifelong tedium of frontier duty with a display before the Emperor himself. Everybody knew that Constantine was here looking for units he could detach for his looming war with Licinius, Emperor of the east. Having grown up at their fort, with families of their own and roots generations deep, many of the soldiers here probably couldn’t even imagine how it would be to serve under an emperor on a long campaign in a foreign land. But they were still Roman soldiers, and beneath those hand-me-down armour plates, hearts must have been beating with anticipation.

At last the Emperor himself rode by, a burly, powerful man, accompanied by his generals and aides. They all wore expensive, brightly coloured parade armour, including elaborate helmets with carved carapaces and bejewelled masks. The soldiers stood proud before their Emperor’s inspection.

Cornelius, ever the traditionalist, murmured a commentary in Thalius’s ear. ‘Quite a mixture of symbolism - don’t you think? Here you have a Roman army with its roots, let us not forget, in the citizen-farmer communities of Latium. But see the Emperor and his cronies in their fancy parade armour. I’ve heard travellers to Egypt and Persia say that the more centralised the society the more you see the flaunting of such symbols of rank ...’

Aurelia hissed, ‘Oh, do shut up, Cornelius, you bore. It’s less than an hour before our audience with the Emperor.’

‘Since I arranged the audience,’ Cornelius said stiffly, ‘I’m well aware of it.’

‘Is the boy ready?’

Thalius glanced across at Tarcho and Audax, who sat in the pavilion a few rows behind the others. The old soldier was looking reasonably smart in his own polished armour, though he obviously longed to be out on the field with the troops. Audax had been washed, dressed in a smart new tunic, his hair trimmed and combed. He still looked thin and pale, though, much younger than his years - he was still the sun-starved worm Thalius had found in Dolaucothi. And yet he was the key to everything.

‘He’s ready,’ Thalius said to Aurelia.

‘All right,’ Cornelius said. ‘Let’s go over it one more time. I will lead you in, Thalius, with the boy. I’ve managed to interest the Emperor in the Prophecy etched on the boy’s back. He is fascinated by such things, in his credulous soldier’s way. Then I will call you forward, madam—’

Thalius said, ‘And with Aurelia’s help I will show him how to read the acrostic.’

‘A prophecy of his own murder,’ Cornelius said with a cold grin, just softly enough not to be overheard, loudly enough to make Thalius fear that he had been.