These points were important to Negrinus. The murder charge against him was still down to be heard in the Senate. As far as I knew, the two informers had made no move to withdraw their petition. So what would they do now? Silius still, after all this time, needed to show that Rubirius Metellus had not committed suicide. Would they now demonstrate that it was Saffia who killed him? `Laco, I have come to view these men as shameless in their self-interest. I had supposed Paccius was keeping Bratta at his house to stop me finding the man. But perhaps it was for more despicable reasons. Paccius may have been making sure he could turn Bratta in, if he needed to support a scheme to denounce Saffia.'

Laco pursed his lips, looking thoughtful. `The vigiles are holding this man. But will he clear Negrinus?'

`I have brought you Celadus, who can do that. Corroboration from Bratta would be useful, but it's probably not essential.'

Verginius Laco, as was his wont, heard me out in silence, thanked me politely, and gave away nothing.

Even so, I was not too surprised when, three days, later, Helena and I, and her two brothers, were invited to visit the Metelli that evening. Clearly it was not a social invitation, or we would have been offered dinner first. Hoping that somebody wanted to open up, we dressed carefully – Helena in a matching dress and stole in tawny shades, with a full set of silver jewellery; me in a clean tunic, one with itchy rope patterned braid cluttering up the edges. At Helena's pointed suggestion, I had had myself shaved. While I was submitting myself to the cut-throat blade, she read through all our case-notes.

We travelled in her litter, snuggling up under a rug, which helped the time pass as the bearers trudged slowly through the winter night. For reasons of her own, Helena had made them take a long detour, going up and over the Aventine above our house. It was a steep climb, apparently just so Helena could pop in with a bunch of winter celery for my mother.

Ma cannot have been expecting this treat, for she was entertaining Aristagoras. He was her eighty-year-old man-friend, a source of much curiosity and highly strung gossip in the family. When we arrived, the amiable fellow grinned a lot then tottered off like an arthritic grasshopper; Ma claimed that he had just called to bring her some cockles.

While I looked around for a new shellfish jar and failed to find it, Helena got down to her real business: ‘Junilla Tacita, we are on our way to see some people and I don't have time to track down Ursulina Prisca. I wondered if by any chance you could help me clarify something…'

`I know nothing about anything,' Mother moaned, in a pathetic mood. Evenings tired her. She was ready to nod off in her armchair, and probably glad we had driven out her admirer.

`Oh, you know everything! I was so glad you came with me to see that wet-nurse -'

`Euboule? Don't trust her!'

`No, I didn't care for her at all,' Helena agreed. `But one thing puzzles me. I have remembered that Ursulina told me not to take baby Favonia there because, she said, "you might never get the little darling back" -'

`Have you done anything for that poor woman, son?' Swiftly distracted, Ma rounded on me.

`Ursulina? Our next job, Ma,' I lied.

`Oh you take your time, my boy! She's only desperate.'

`No, she's not. She's stirring up trouble in her family – something I would never do in mine, of course.'

`The woman needs help.'

Ursulina needed another interest in life. I just said mildly, `We will help her, but she may have to wait. I'm desperate myself. I have to find half a million sesterces for a vicious compensation claim -'

`So you let someone down?' sneered Ma, so unimpressed by my plight she had failed to take in the large figure.

`He was tricked by wicked men,' Helena defended me. She managed to get back to her original query: `It may help Marcus if he knows what Euboule and Zeuko have been up to. He needs to know tonight.'

Ma stared at her. Luckily she was weary, wanting to be left alone. Her normal readiness to spar was weakened. `Oh you know what those wet-nurses are like…' Helena waited. `Rich women dump their babies there, and half the time – so Ursulina says – they forget what the children even look like. They have no idea if what they get back after a year or two is even theirs.'

`I would recognise Sosia Favonia!'

`Of course you would. Then again -'Ma, who disapproved of wetnursing, went off into a rant. `Of course some of those women do it on purpose. They don't want another pregnancy so if they've got a sickly little thing they take it along and make sure the wet-nurse replaces it if misfortune strikes -'

`That's horrible.'

`Not if it suits everyone. I could have exchanged a few of mine quite happily!' Ma cackled, and made sure she glared at me.

Helena Justina rocked back on her seat and stared at the ceiling, her mouth pursed.

`Still,' said Ma crisply. `We know exactly what happened in this case of yours.'

`We do?' I asked.

Ma sounded complaisant. `Oh, Ursulina and I worked it all out for you.' I breathed slowly, keeping my expectation in check. `We could have solved it for you days ago.'

`Well pardon me, why didn't you say something? So, Mother darling, what's the dirty secret?'

`Son, it's obvious. Someone creeping up the stairs by moonlight.'

`What?'

`Euboule and her daughter probably know. That woman, Calpurnia must have put one over on her husband. Good for her!' chortled my mother. `She must have had a boyfriend. Don't ask me who – it's your job to spot the culprit. Friend of her husband's, or a pretty slave. So this young man the fuss is all about -'

`Her son, Negrinus?'

`You ask them, Marcus. I bet he was not her husband's child.'

`You could well be right,' Helena said. `The wife upset her husband, which could mean that he found out one day; the son was disinherited; people blackmailed the family. They call the son Birdy -'

`He's a cuckoo,' snorted Ma. `A rich little cuckoo in the fancy nest.'

Helena fetched Ma her house slippers. I made her a warm drink. Then we continued on our way to visit the Metelli. Perhaps we were about to learn their family secret. Perhaps we already knew it.

On the other hand, nothing was simple in connection with this family. Helena agreed that it was quite likely the children of Calpurnia Cara still harboured some surprises.

LVI

We were escorted into the white salon. Fine oils burned in the gilded lamps, gleaming on the nifty bronze Aphrodite in her matt plastered niche. The two sisters, Rubiria Juliana and Rubiria Carina, were displaying handsome jewellery as they sat in genteel postures on the best-positioned ornate couch. Their husbands spread themselves on other plush upholstery, one on each side of the women. Negrinus sat gloomily one along from Verginius Laco, feet planted in front of him and elbows on his knees; beyond Negrinus was a tanned, thickset man we had never seen before. Helena and I took places near the scowling Canidianus Rufus, forming a half-circle. We ended up opposite the stranger. He stared at us curiously, and we returned the compliment.

The Camillus brothers arrived last, though fortunately not too late. They redeemed themselves by their smartness. Each wore well-buffed leather boots, tight belts, and identical white tunics; I detected their mother's hand in their overall neat turnout. Neither had his usual hair parting and I reckoned the noble Julia Justa had tackled them both with her fine bone comb before letting them loose.

Justinus immediately nodded a greeting to the thickset man. That confirmed he was Julius Alexander, the freedman and land agent from Lanuvium. Despite their tussle over Perseus, when the lads stationed themselves on the remaining seat Justinus sat adjacent to the freedman. Both then leaned over the curled arms of their couches and muttered in an undertone about the vigiles' fatal handling of the door porter.