‘Before he dies?’ Caesar tilted his head slightly to one side. ‘I am not going to kill him, Marcus. First I must find out why he’s here. There’s more to it than buying slaves.’

‘What if he’s been sent to attempt to kill you again, sir?’

Caesar pursed his lips. ‘That’s a possibility. On the other hand, maybe Crassus is just sending me a subtle message. Reminding me that he still has some hold over me. I must ensure that Decimus is closely watched.’

‘I’ll do it.’

‘No. He would recognize you at once if you bared your face to him. I’ll tell Festus to do it. You stay clear of him for now, do you understand?’

‘Why?’ Marcus growled. ‘This is the man who ruined my life. Now he’s in our hands. You gave me your word that you would have him hunted down and forced to reveal where he had my mother taken.’

‘I know. And I honour my promises, Marcus. But you must not forget your place.’ Caesar drew himself up and stared down with an imperious expression. ‘I am a proconsul of Rome, and you are my servant. I will not have you speak to me like that again. Not if you want my help. Is that clear?’

For a moment Marcus wanted to shout his defiance into Caesar’s face. Tell him that he did not care who Caesar was. All that mattered was saving his mother. Then he took control of his thoughts again, angry with himself for being weak- minded. He was exhausted, but that was no excuse. He had to be strong and control his feelings. Caesar had the power of life and death over him, and the power to determine whether his mother was found and set free, or left to rot in a chain-gang. He could not save his mother without Caesar’s help. He took a deep breath and replied bitterly. ‘Yes.’

‘Yes?’

‘Yes, sir.’

Caesar continued to stare at him for a moment before nodding. ‘That’s better. You must remember your place in this world, Marcus. I will always be in your debt for the services you have rendered me, but there is a limit to what I am prepared to tolerate from you. Overstep the mark again and there will be consequences. Understand?’

‘I understand, sir ... I apologize.’

‘And I accept your apology.’ Caesar smiled and patted him on the shoulder, as if the tense exchange had been instantly forgotten. ‘Don’t concern yourself over Decimus. When the time is right he will be called to account for the wrongs that he did to you and your family. In the meantime we should consider ourselves fortunate that Crassus has seen fit to place Decimus in my hands. I wish I knew precisely what Crassus was up to. It’s possible that he merely wants to place yet another spy in my camp.’

‘Another spy?’ Marcus raised his eyebrows. ‘You mean there are others, sir?’

‘Of course there are. I know most of the identities of those who are working for my political rivals, and my political enemies. I make sure that I feed them enough information to keep their masters happy without giving away my real plans. Just as they have uncovered some of my spies and are careful not to reveal too much to them in turn.’ Caesar paused as he saw the shocked expression on Marcus’s face. He laughed heartily. ‘Surely you aren’t really surprised, my boy? Not after all the plots and conspiracies you experienced in Rome last year?’