‘Of course.’ Maximius glanced round suspiciously and then lowered his voice so that it was barely more than a whisper. ‘Who else can I trust in this matter, Macro? Tullius is an old woman. Felix and Antonius are too young to be trusted with secrets, and uncovering secrets. You’re the only one of my officers I can rely on. I want this traitor identified and brought to me in chains. You’re the perfect man for the job, Macro.’

‘Yes, sir.’ Macro nodded. ‘What exactly do you want me to do?’

‘Just talk to the men. Nice and easy. Don’t push for information. Say as much as you need to, nothing more, and just listen. Then report back to me.’

‘Yes, sir.’

‘Right then.’ Maximius turned round and nodded towards the last patrol standing at ease by the gate. ‘I want you to take them out today. The guide says there’s a few small farms to the east. They might be worth checking out. After all, Cato’s lot will need food. If there’s any sign that the locals have been harbouring them, you know what to do. Make an example of them.’

‘Yes, sir.’

‘The optio there, Cordus, is from Felix’s century. He’s a good man, you can rely on him. Now you understand your orders?’

‘Yes, sir.’

The cohort commander paused a moment to look intently at Macro. ‘Report everything to me when you return - everything.’

Macro saluted. ‘I understand, sir.’

‘Good luck, then.’

At noon Macro gave the order for the patrol to halt. Sentries were posted at each end of the track and the rest of the men gratefully slumped down on to the ground and reached for their canteens. The sky was a piercing blue, except for a scattering of puffy clouds drifting slowly away to the south of the marsh. Macro craved some shadow and looked at them longingly. The sunshine beat down on the still air that hung over the marshland and every man in the patrol was sweating heavily. The felt liner inside his helmet was drenched and Macro could feel beads of sweat running down his forehead, and dripping on to his cheeks. The heat was exhausting and the men had grumbled about their lot all morning, until Macro had lost his patience and ordered them to shut up. Thereafter they had marched along in silence, growing steadily more surly as the guide led them along the narrow winding paths, through rank-smelling shallows and thickets of gorse without encountering any sign of habitation.

‘Cordus!’ Macro waved him over. ‘Ask him how much further we have to go.’