I swore. Maia (a vibrant, energetic girl who had a thicket of dark curls, jauntily bound with crimson ribbon) managed to look guilty about letting the acolyte run away. Then a tremulous voice came from Mother's bedroom. She had been awake and listening all the time. 'I'm just a helpless old woman, racked with suffering Someone must go after poor Ganna!' That order came out crisp enough.

Annoyed, I demanded a clue where to start. In a little whisper, which fooled no one, my mother named the Temple of Diana on the Aventine. Diana: virgin goddess of the moonlit groves, with the big thighs and the over-excitable bow and arrows. Well, that made sense. Any woodland priestess would feel well at home with the haughty huntress. One thing I ought to have remembered right at the start of this mission was that the Temple of Diana was by tradition a safe haven for runaways.

When pressed, Ma meekly admitted young Ganna had regularly prayed at this temple… 'Oh Hades, Ma; didn't you suspect something? Why would Ganna want to pray to Diana? No one from Germania Libera honours the Twelve Consenting Gods!' A nagging recollection came to me: 'You keep her in?' 'Except when we make a little trip together to a market or temple.' 'Has she said anything?' 'She fooled you plenty. There's a lot she's holding back.'

Stupid! I should have picked up the clue. At the very least, messages were being passed. At worst, Veleda herself had been in hiding at the temple, and Ganna had been colluding with her. If that had been true, probably neither Ganna nor Veleda would be there now. 'Why didn't you say something?' 'Oh son, I never interfere.' Dear gods. 'I have to leave.' 'Don't rush!' cried Maia. My sister had a fast, angry way of dealing with crises. 'First off, I can read the auguries. As soon as Mother owned up what a scam the girl had been pulling, I nipped to the temple myself, Marcus. The priests denied all knowledge. They will only say the same to you. In any case -' This was the clincher; my sister knew it – 'Helena wants you back at home. She said to be there prompt, good-tempered and clean. Titus Caesar has invited you two and her parents to the official feast tonight at the Temple of Saturn. So you'll go – or you're damned to the memory.'

I closed my eyes in dread. An endless official banquet, in the presence of a god's effigy and those two stiffs, the imperial princes gamely pretending to be men of the people while flying nuts hit their gold braid and drunks spewed on their orbs of office – was not my idea of a social life. Even Titus and Domitian would probably prefer a night in with a game of draughts. 'Look on the bright side,' Maia consoled me. 'It gets you out of puppets up at Pa's house.' A thin wail of agitation came from Ma at the mention of our absconding father. Maia and I exchanged wry smiles. Oh flying phalluses, stuff the priestess. Since it was a festival for ending grudges, I kissed my sister tenderly, kissed my mother even more devotedly, dodged Ma's flailing arm as she tried to box my ears, and went home to take my wife out to an alfresco dinner with the ancient god Satumus.

XXXIX

'I am sorry, Marcus. But avoiding the invitation would be impolite. '

Helena meant, it would be too political. When the Emperor called, no one was otherwise engaged. Refusal would finish us. We would not be asked again. Our public life would end. Once, I had not given a stuff about my career in public life; now I had a family.

I even had slaves to provide for. They liked to enjoy the full spectrum of Roman life. Galene and Jacinthus had now completely abandoned their duties. They were playing Soldiers on a board marked in the dust in the entrance hall. It was true the dust would not have been there if I had bought a cleaning-slave. So I might not have minded – but they were using my best dice.

'What will you do about Ganna and Veleda?' Helena fretted, as I brought her up to date on my day. I had sent all our legionaries to observe at the priestess's Aventine sanctuary. No point making too much of it; I strongly doubted Veleda was there. Helena thought the men had just gone out drinking. In case she decided I was planning some manoeuvre with the soldiers, I let her think it. I was a thoughtful husband. 'This is typical,' she said with a sigh. 'There is action at a temple – but you will be stuck in the wrong temple!' 'True, my darling.' I concentrated on fastening my party shoes. Glancing up, I saw her expression suddenly still. For a beautiful woman with a mainly placid temperament, Helena Justina had a stare that could bore holes in stone. Parts of me felt molten. I loved her as much as a man could love anyone, but I wished that girl would occasionally consent to be bamboozled.

She had detected that I was hoping I would not be in the wrong temple for long. The Temple of Saturn is the oldest in the Forum provided by a private sponsor. If you stand where the stairs used to come up from the Tabularium – I mean, where the Temple of Vespasian and Titus has since been squeezed in, under the shadow of the Capitol, forming that squash with the Temple of the Harmonious Gods and the Temple of Concord – that's assuming you can bear to be in an area of so much suffocating harmony and goodwill- then Saturn's antique shrine juts out straight in front of you. Clad in marble, hexastyle, adorned with Tritons, it will be blocking your view of the Basilica and the Temple of Castor. The ship's prows celebrating naval battles and the Golden Milestone with the distances to the world's major cities will be visible in front of it, if you are waiting for a friend and want a distraction to stop you attracting the notice of prostitutes.

The heavy vaults beneath the podium guard the civic treasury. The platform is high, to accommodate the slope of Capitol Hill, and the front steps are unusually narrow, to fit in against the sharp angle of the Clivus Capitolinus as it comes into the Forum, around the Tarpeian Rock. We arrived that way on foot; I glanced up as I always did, just in case any women traitors were being flung off the rock that night. With Veleda in town, it was a possibility. In the sharp night air, sounds carried; I even thought I heard honking from the Sacred Geese of Juno right up on the Arx, public birds whose official guardian I had once been, in a mad period of civic responsibility. Above, anxious crows and other birds were wheeling about the dark sky, upset by the multitude of lights that filled the Forum.

On the steps and in front of the temple, the banquet had been set out. Saturn's image, a large hollow statue, was made from ivory, so to keep it from cracking it was kept full of oil. The statue had been brought out from the interior. The ancient deity had his head veiled and was holding a hooked sickle. His feet were normally bound together with wool (no idea why; perhaps the sacred one is prone to absconding to seedy bars). The wool had been ceremonially unbound for this occasion. Oil had leaked out around the couch when he was put in position. The public slaves who moved him every year were efficient and reverent, but just you try shifting an outsize statue filled with viscous liquid. The weight was appalling, and as the oily ballast started slopping to and fro, the deity wobbled dangerously. The priests always got in the way trying to supervise, so the slaves grew ratty and lost concentration, with inevitable leakage. They would fill him up again, but not until they took him back indoors.

Helena and I, and her parents, were privileged, in theory. The whole city was supposed to attend tonight, but fitting them in would be ridiculous so hungry crowds were clustered in the darkness all around the periphery. Vespasian was a parsimonious emperor who loathed his obligation to supply endless public banquets. This feast was a lectisternium, a banquet offered to the god in thanks for the new harvest; Saturn's oversized, hoarily bearded, goggle-eyed image presided on a giant couch, before which were placed tables laden with rich fare. Traditionally, the fare was rich enough – and had been hanging around in kitchens long enough – to cause severe stomach upsets in the human diners who would eventually devour it (paupers, who were already queuing hopefully at the back of the temple). There were other tables, less opulently covered, where mediocre lukewarm foodstuffs in meagre quantities were available to us lucky invitees.