With a sudden flare of insight Cato realised that Tigellinus was as fearful as he was. If his masters had given separate orders to either Cato or Macro, or both, then it was clear that they did not trust him enough to share that information. Worse, they might actually distrust Tigellinus enough to order a separate attempt on the Emperor’s life in case Tigellinus failed. Cato had to make his response quickly, before the centurion turned his attention to Macro. He made his decision. If the Liberators were on the verge of attempting to overthrow the Emperor then it was important to disrupt their plans.

‘Yes, sir,’ Cato replied in a wary tone. ‘Sinius told me of your orders, and said that I was to carry the assassination through if you failed for any reason.’

Tigellinus drew a long, deep breath and exhaled through clenched teeth. ‘I see. And you did not think to tell me this?’

‘Centurion Sinius told me to watch you and act if I needed to. He did not say that I should make you aware of my orders. I assumed that you either knew already, or that you weren’t supposed to know of my part in the attempt.’

Tigellinus stared at Cato for a moment and then switched his gaze to Macro. ‘And you? What did you know of this, Calidus?’

‘Nothing, sir,’ Macro answered truthfully.

Tigellinus turned back to Cato. ‘Why is that, I wonder?’

Cato shrugged. ‘A secret shared is a risk doubled, sir. Perhaps that’s why Sinius told only me to keep a watch on you.’

‘Perhaps,’ Tigellinus mused. ‘At least I know where I stand in the eyes of our good friends, the Liberators.’

‘Sir, I don’t know if I should have told you this. Sinius didn’t expressly say that I shouldn’t. But perhaps it would be best if he did not know we had spoken.’

Tigellinus’s face slid into a crafty expression. ‘I shan’t say anything, for now, Capito. But in future, if Sinius tells you anything, then you tell me. Is that clear?’

‘I’m not certain that would be wise, sir.’

‘I’m sure it wouldn’t. But if I were to tell Sinius that you spilled the beans so easily then I doubt he would consider you a reliable, or inexpendable, member of the conspiracy. You understand? In future, when he speaks to you, you speak to me. If you don’t then I shall make your life difficult, not to mention dangerous. Clear?’

‘Yes, sir.’ Cato nodded. ‘As you wish.’

‘Quite. Now, out of my way. I have to get this bloody mud off me and my kit.’

Cato and Macro stepped aside and a foul odour wafted into the air between them as Tigellinus strode by. They watched him reach the end of the colonnade, enter his quarters and shut the door with a crash.