Macro was momentarily stuck for an answer as his mind flashed back over recent years. The street fighting in Rome, then the campaign in the sweltering heat, glare and dust of southern Egypt. Before that, the suppression of the slave revolt in Crete and the defence of Palmyra against a horde of Parthians. And earlier, dealing with fanatical Judaean rebels, a secondment to the imperial navy in a campaign against a nest of pirates plaguing merchant ships in the Adriatic Sea. That was after a long period of service with the Second Legion which had guarded the Rhine frontier, before being assigned to join the army that had invaded Britannia and crushed the native armies led by Caratacus. It was a notable period of service by any standard and Macro had won his promotion to centurion on merit – unlike some, who owed their position to powerful family connections. Yet Macro was not prepared to make a song and dance about it in front of the governor. He cleared his throat.

‘I’ve been on detached service for the last few years, sir. Before that I served with the Second, on the Rhine, and afterwards here in Britannia.’

‘Detached service? That is something of a euphemism for spying these days. What exactly was the nature of your, ah, detached service?’

‘I am not at liberty to tell you the details, sir.’

‘Then at least tell me who you were working for.’

Macro felt uncertain, and glanced quickly at Cato, but his friend’s expression was fixed and unreadable as he faced forward. Macro took a deep breath. ‘The imperial secretary, Narcissus.’

‘You worked for that snake?’ Ostorius’s eyes narrowed. ‘Are you here on his orders?’

Macro was angered by the suggestion and sucked in through gritted teeth, but before he could respond Cato spoke up.

‘If that were the case, sir, then we’d hardly divulge that information. In any case, I give you my word of honour that we no longer serve Narcissus. We are here as soldiers. To serve you, the Emperor and Rome. Nothing more.’

‘Your word of honour, eh?’ Ostorius sniffed. ‘There’s precious little of that commodity being traded in Rome these days.’ He leaned back on his stool and rubbed the small of his back. ‘I have little choice but to take your word for it. But I warn you, if I get one hint that either of you are here for any reason other than soldiering, I’ll throw you to the natives and let them deal with you. The Druids have some very interesting ways of disposing of their prisoners.’

‘We know that, sir. We’ve seen it with our own eyes,’ Cato responded, resisting the urge to shudder as he recalled his encounter with the Druids of the Dark Moon, back in the early days of his life in the legions when he served as a lowly optio in Macro’s century. Brief visions of the sacrificial victims and the wild appearance of the Druids flitted before his mind’s eye and Cato hurriedly thrust all thought of them aside.