The Metelli, as I might by then have expected, kept their porter in situ all day. I observed this from the same unfriendly snackbar where I had rested my trotters on the counter yesterday. This meant I might have to wait around for hours before that other informing trick: knocking on the door at lunchtime when the porter takes his meal break. Luckily, I did not need to wait so long. While the door was open for a delivery, I heard the porter ask another slave to stand in while he went off for a pee.

Thank you, gods!

(Which reminded me again that I was Procurator of the Sacred Geese of Juno, and I ought to say hello to my fat feathered charges, now I was back in Rome.)

`Morning. My name is Didius Falco; I was here yesterday on business with your mistress. Could I possibly see her again for a few minutes, please?'

`I'm supposed to ask the steward,' the stand-in said. `I think.' He was a kitchen worker normally; he had an apron on, stained with oil and sauce.

`That's right,' I agreed, smiling helpfully. `The other Janus – what's his name?'

'Perseus.'

'Perseus asked the steward yesterday.'

`Oh he asked him, did he? Well, that's all right then. She's in the garden; this way, sir -'

The stand-in had left the door open. Assuming my helpful guise, I pointed out that while he escorted me to find Calpurnia Cara, wrongdoers might sneak in. That worried him. So he stayed there but gave me instructions how to cross the atrium, pass through a colonnade, and find the garden area by myself. I handed him a quarter denarius. It was the least I could do. I knew, though he apparently did not, he had just earned himself a severe beating for letting loose an informer in the house.

It was worth a quiet wander around. I like gardens. This peaceful enclosed space between wings of the silent house had a damson tree and ancient twining plants fastened up pilasters. Inside the house there was that faint impression of not having enough slaves around to keep the place smart, but the garden was well tended. Puddles and damp earth showed that plants had been watered, though whoever brought the buckets had moved on. I could see at once that Calpurnia was not there.

This was tricky. Or rather, for an informer it was excellent.

I spent a long time walking about. No town houses have enormous grounds, but I explored colonnades, peered into empty ground floor rooms, poked into stores. Though light on attendants, it seemed a well-run, organised establishment. That fitted. Corrupt nobles have to be efficient, or they get found out. True, Metellus had been exposed – but he had fallen victim to an informer, and informers notoriously target victims unfairly. Left to himself, he might have fleeced the state and its contractors for many more years and died `with honour'.

At the back of the house soared the old Servian Walls, the ancient fortification we called the Embankment. Approaching, quite suddenly I came upon a woman alone. She was dressed in dark clothes, though I thought that reflected her glum nature rather than mourning. I had reached the farthermost part of the garden, a small patch of dry earth with vegetable trenches and a fan-trained fig tree. She was standing, apparently in a reverie, on a gravel path that was flanked by tired herbs, outside an outhouse that had been partly carved into the side of the Embankment.

`Damned wasps' nest,' she muttered, seeing me. She was pretending her eye had just been caught by something. It sounded mundane, but her face had hardened. `What are you doing here? Who do you think you are?'

`Would you believe a wasp exterminator?'

`Stop your nonsense.'

`I apologise.' She was right about the nest. Insects were flying to and fro, entering the roughly constructed building above a corner of the doorway. `Marcus Didius Falco -'

'Ah yes!' she jumped in, with an acid tone. `From Silius. You sent your wife on an exploratory mission yesterday.'

She turned away from the shack, which was chained up. I noticed she was carrying a large bunch of metalwork – the traditional matron, in possession of the household keys. 'Calpurnia Cara, I take it?' I asked, a neutral response to cover up being caught out. The woman, who had a permanent expression of distaste, nodded slightly. Trying to distract her, I asked, `What do you keep in the garden store?'

`Unwanted household goods. Your wife was unwanted too, I may say.’

It was a neat link, but I decided not to play word games: `Helena Justina was merely curious about the work I have taken on -'

I am not a fool, Falco.' Calpurnia Cara was annoyed, though at the same time she somehow accepted that annoyance was bound to happen. She began to walk back to the house; meekly I went with her. She looked to be in her late fifties, a heavy woman, her step slow and a little awkward. Had she been my grandmother, I would have offered an arm, but this grand matron was far too austere. She took pleasure in telling me how she had outwitted us: `My adviser dined here yesterday. We have to be careful; my family has attracted unpleasant notoriety. I showed him a list of visitors. Africanus spotted her.'

Paccius Africanus had taken an interest in me, then. He must already have known my connection with Helena Justina, before he saw yesterday's list. Our association was unusual, yet Helena and I were hardly well-known names in public life. So: Paccius Africanus had been digging.

`Who let you in?' Calpurnia demanded. It boded ill for my crony on the door.

'Perseus had been called away -'

`Called away?' I had the impression Perseus might have caused exasperation in Calpurnia before. Well, that would make him a typical door porter.

`Call of nature.' In fact I was starting to think that nothing as easygoing as nature would occur in this establishment.

`I'll see about that. What did she want him to do? Pee into the atrium pool? It has been known; put-upon porters are aware that their nagging owners use the run-off from the pool as spare drinking water.

We had reached the colonnade that fronted the atrium. I was led smartly round the sphinx and the pool. I was on my way out.

`I have nothing to tell you,' Calpurnia informed me. `So stop bothering me. I know you have been to our formal witnesses and they have affirmed all that happened.' She was keeping very well informed. The normal porter was back, looking unconcerned at his lapse, as porters tend to do. 'Perseus! Put this man out.'

`Had your husband discussed his intentions with you?' I squeezed in.

`Metellus did nothing without my knowledge,' Calpurnia barked.

`Did that include his business life?' I enquired coolly.

She pulled back quickly. `Oh none of that had anything to do with me!' As if a stronger denial were called for, she went on, `Load of spiteful, invented stupidity. Viciousness. Collaborators. Silius ought to be exiled. Destroying good men -'

Goodness played no part in the business ethics of the Metelli, as I knew the facts.

I was leaving as ordered, when Calpurnia Cara called after me. `Your wife was trying to extract the whereabouts of my ex-daughter in-law.' I turned back. `I am sure my staff were very helpful,' Calpurnia stated in a dry tone. `Don't bother with Saffia Donata. She has nothing to do with any of this and she is a mischief-maker.'

`Nonetheless, I am sorry to hear of your son's so recent separation from the mother of his children.' Since the Metelli were so keen on form, or the appearance of form, the dig seemed apt.

`Child!' barked Calpurnia. `Her other brat came from another source.' I raised an eyebrow at her wording. Had immorality occurred? `Previous marriage,' she explained impatiently, as if I were an idiot. Clearly nothing untoward in the bedroom arena could be allowed to touch this family. `We took her on for that reason. At least we knew she was fertile.'