‘Quite beautiful,’ Boudica muttered.

‘It is.’ He nodded, but his mind was still working. The basis of a close friendship was impossible to define. And the same was true of love, it seemed. There was in Macro some ineffable quality that appealed to Boudica. Perhaps it was true of every person; they all possessed some quality of character that called out to its mate in another being . . .

‘Look!’ Boudica raised her hand and pointed to the west.

Cato thrust his introspection aside and saw a bright flicker in the gloom not far from the ridge behind which the sun had set. Then another appeared, and more until the wavering flames seemed to form a shallow ellipse, with a line leading off to the side. The fires had been seen by one of the garrison’s sentries and he sounded the alarm, clattering the point of his javelin against a small bronze cauldron hanging beside the outpost’s gate. A moment later the optio roused himself and bellowed at his soldiers to man the palisade. The door to the nearest barracks crashed open as Macro raced outside, crested helmet in one hand and mail armour hanging over his other arm. Behind him came the rest of the Romans, the last of them making way for Ostorius, just as Prasutagus and his warriors burst out of their quarters and scrambled up the turf inner wall and on to the boarded walk behind the sharpened stakes of the palisade. The sentry continued sounding the alarm a moment longer before Macro shouted to him.

‘Shut that fucking racket up!’

As the last tuneless note died away, Macro lowered his helmet and struggled into his chain-mail vest. ‘Make your report, man! What did you see?’

Before the sentry could reply, Cato drew a breath and called from the watchtower, ‘Fires to the west!’

As the last of the men lined the palisade, Ostorius struggled on to the walkway, breathing heavily. The fires, scores of them now, were well enough established to be clearly visible and there was a hush before one of the junior tribunes spoke up. ‘What is that? It looks like an army on the move.’

Ostorius coughed to clear his throat. ‘That’s Avibarius, I imagine.’

‘Aye, Roman,’ said Prasutagus, his deep voice carrying clearly. ‘It is.’ He glanced up to the watchtower and frowned as he caught sight of his wife. A moment later the structure swayed slightly as the giant Iceni warrior climbed the ladder and then squeezed on to the platform alongside Cato and Boudica. There was a terse exchange in the Iceni tongue before Prasutagus eased himself between his wife and the prefect and stared towards the distant fires.

‘The fires mark the boundary of sacred stones. As the sun dies, the fire gives light to the world. When priests give the order.’

‘Priests?’ Cato took in a sharp breath. ‘You mean Druids.’

Prasutagus nodded.

Cato unconsciously raised his hand to touch his chest where a Druid had wounded him seven years before. There was only a scar there now, but suddenly he felt a chill on the flesh beneath the cloth of his tunic. ‘What does it mean, Prasutagus?’