'Who's that?' squawked Ma, pretending she was unable to make out who had come in. 'Marcus! Is that you creeping about to frighten me?' Her guest turned around quickly. He was nervous. That was good. I stared into those pale eyes – noticing for the first time ever that while one was a watery grey as I remembered, the other was a light hazel. I let him worry for a moment, then smiled at him. I knew how to make it look sincere – and I knew that would cause him more anxiety. 'Fancy finding you here – Io, Anacrites!'

'Io, Falco!' 'I've been looking for you.' I sounded like a bailiff.

'I got your note…' So either the crazy workaholic had been to his office after I was there, or some frightened minion had hotfooted to him with my message. A mad thought struck that maybe he had been there all the time when I went to the Palace, hiding behind a pillar, secretly observing me. Now he had come here to worm out what I wanted before he approached me. What kind of inadequate asks your mother first? As if he knew what I was thinking, he coloured slightly. 'You've got more than my note.' I kept my tone light but ominous. 'Why don't you come in decently?' demanded Ma. That would stop me making the Spy squirm round to look at me over his shoulder. He was on a bench that was pulled tight under the table, so movement was hindered. I was standing, so I could dominate the bastard.

'I'm fine, Ma.' Anacrites was clutching his spoon like a toddler, tantalised by the half-eaten bowl of leeks. 'So you still come to visit my mother, Anacrites?'

'Anacrites is a good friend to a poor old woman.' Ma's usual note of reproof made me sound like a bad son. Since I would never overturn this myth, I did not bother trying. 'I only wish everyone took so much trouble…'

'Just bringing Saturnalia greetings,' he excused himself wanly. 'Why did you want to see me, Falco?'

'You need to do some quick talking, old mucker.' The endearment was fake. I kept smiling. He started to sweat. A severe blow to the head several years ago had left Anacrites with a permanently damaged skull and a tendency to panic at times of tension. He suffered headaches and a changed personality as well. And although I had brought him unconscious to my mother to be nursed back to life (which was how he knew her, and knew her well enough to get free broth), he could never trust me to maintain the insane generosity that had once saved him.

I came into the room and moved around the table. Anacrites tried to relax. 'I've taught you nothing; never sit with your back to the door.' He dropped his spoon. I bent and kissed my mother's cheek like a good boy. She glared at me suspiciously. 'Now then, Anacrites, what do you mean by arresting Camillus Justinus?' I demanded. 'You haven't!' cried Ma. I perked up as he took the arrows. 'What's he done? He's a lovely boy!' 'Some palace mistake,' I told her. Anacrites was glowering. 'State business,' he bluffed. 'State incompetence,' I snorted back. 'Young Camillus is a free Roman citizen. No one may lay hands on him.'

Anacrites was about to make his favourite boast, that he could do anything because he was the Chief Spy – but he paused. I was invoking the law. It was forbidden to imprison a citizen; being chained breached a free man's rights. Quintus had the right of direct appeal to Vespasian if he was manhandled, and for wrongful arrest he could claim massive compensation. Anacrites' official budget wouldn't cover that. 'This is an issue of the highest security.' His voice became haughty. 'When the barbarians threaten, sometimes liberties must be suspended.' He added insincerely, 'I don't like it any more than you do, Marcus.'

I had never allowed him to use my praenomen. Sitting in my mother's house with his sly snout in a foodbowl did not make him part of my family.

'The barbarians are cosy in their forest. One woman is your supposed "threat". She must be frightened and we know she's feeling ill. Some terrorist! Never forget,' I warned him, staring at his head suggestively, 'that I know where your weakness is.' His right hand went up; he brushed back his hair as if to protect his once-holed skull, though he must be aware I had not been referring to his wound. My mother shook her head at me reprovingly. I grinned at her; if my laddish brother had grinned like that she would have turned coy, but it failed to work in my case. I never learn. 'Now then, old fellow; you and I are old compatriots, especially after Leptis -' Leptis Magna, where Anacrites had put himself outside the law, was my big threat. 'I just warn you, Justinus' father is intending a personal appeal to his old friend Vespasian. I've managed to put off the senator until tomorrow, but if you want to keep your job, produce your captive before then.' 'Impossible -' 'Better to give him to me voluntarily.' 'Falco, I can't -'

'You are the Chief Spy; you can do anything you want.' He moved restlessly, as I enjoyed myself Irony is the informer's friend. Spies may be devious, but they have to take themselves seriously. 'Anyway, what in the gods' name do you want him for, Anacrites?'

The Spy glanced at my mother. Ma jumped up at once, crying huffily, 'Oh I know when I'm not wanted!' She swept away into her bedroom; its door had been rather firmly closed until now. I had been hoping Ma had hidden Ganna, Veleda's acolyte, in there to stop Anacrites seeing her. It was two days since I left the young girl in Mother's charge and I needed to check up on her, but it was impossible with the Spy here.

'I wouldn't dream of upsetting your mother. I know she is discreet,' Anacrites muttered apologetically. I knew she was bound to be listening. Rushing from the room – and then getting her head against a door to eavesdrop – was an old trick. 'Junilla Tacita is the best of women. I never forget what she did for me.' I never forgot what she did for him either. And my own stupid part in it.

I swung myself over the end bench where my mother had been sitting, so I could gaze at him directly. There was a vegetable knife on the table, which I played with to worry him. 'Well, now you've upset her feelings, let us get on with it! Is arresting Camillus a misguided ploy for finding the priestess?' 'He knew her in Germany.' 'I knew her too. Why don't you arrest me? That way at least you gain something: you won't have the embarrassment of me finding her before you do.' 'Justinus had intimate relations with Veleda,' Anacrites insisted. How in Hades did he find that out?

'Five years ago, perhaps. Now he is a married man and a father, and but for your interference, he would have forgotten her. Instead,' I said heavily, 'you have rekindled any loyalty he had for the damned woman. 'He is in love with her,' Anacrites sneered. 'No he's not. He told me at the time.' 'He lied to you.' 'He lied to himself,' I said easily. 'He was a boy, that's what boys do. Time moves on. The fact is, he did not know Veleda had been placed in that stupid "safe house", the Quadrumatus villa' – I hoped Anacrites himself had selected it. I took a chance. 'He has not contacted her -' 'You don't know that!'

So Anacrites didn't know either. 'Take my word. When your ridiculous goons arrested him, he was attempting a reconciliation with his wife.' 'His wife,' sneered Anacrites, 'who believes that her husband is leaving her to pursue his forest love.' 'She's wrong,' I replied lightly. There was a silence. Anacrites could no longer bear to be kept from his cooling broth. I expect Ma had told him to eat it up quickly while it was good. As he tucked in, I waited. From time to time I stabbed Ma's knife on the board in front of me. Once I picked it up by the old bone handle, and aimed a throw at Anacrites, as if unconsciously.

With the issue of Just in us' release still unsettled, the Spy decided to enrage me by discussing foreign policy. I refused to play. Eventually he turned to foreign women. Ignoring his own Eastern looks and Greek forename, he had the ex-slaves' common snobbery: he counted as a true Roman, but all other foreigners were second-class invaders. Anacrites asked about Claudia Rufina; he knew she came from Baetica. The fool must have the innocent girl on some blacklist. 'Why is Camillus Justinus – who, as your mother said, seems a "lovely boy" – so obsessed with foreign women?'