`Any idea where Petronius Longus is, Falco?'

I had a good idea, and I preferred to keep it private. `He's following up an interview. I can track him down.'

`Good.' This was the sunflower-seed eater, neutral and standing well back. `I'll leave it to you to tell him then.' Thanks, tribune!

Gaius Baebius and I left the building. With the usual difficulty I managed to shed my brother-in-law, who always liked to cling on when he was not wanted. As the streets grew darker, I walked somberly from the Twelfth sector, where the Fourth had their headquarters, and down the hill to the Circus side of the Aventine. I could hear gulls squabbling over the Tiber wharves. They must always be there, but tonight I noticed them with resentment. Tonight was not the time to be reminded of the sea.

Everywhere seemed full of excited parties going out to dinner. Horse-faced women shrieked. Crass men chivied their trains of slaves to trot along faster. All shopkeepers looked malevolent. All passers-by had the air of would-be thieves.

A meek porter admitted me to Milvia's elegant house. I was told Florius was still out. No one seemed perturbed by it, even though respectable householders normally show up at home in the evening. If he was going out to dinner he ought at least to change his tunic – and some wives would expect to be taken along. No one had much idea when they might expect him back either. It seemed routine. Warily I asked whether an officer of the vigiles had visited that evening, and was told he was talking to Milvia in private.

As I feared. Another allegedly respectable husband was marauding off the leash. Petronius Longus could behave like a real boudoir bandit.

I was shown once more into the salon with the thin-legged Egyptian furniture. No one else was there. The house seemed very quiet, with not much going on. The whole time I was there Milvia, the young lady of the house, failed to appear.

I waited. After a few minutes Petronius walked in. He was wearing a green tunic that I had last seen the night he and Silvia dined at our apartment. He had bathed and changed, but there was no special odour of unguents. I might have been wrong; this was hardly the debonair adulterer at work. He looked perfectly normal – calm, steady, utterly the man in charge. My abrupt appearance here gave him some warning. We were such close friends he immediately knew far more than I had done when I set eyes on Gaius Baebius.

But I would still have to tell him.

‘What's up, Falco?' Petro's voice was quick and light.

`You won't like this.'

`Can things get worse?'

`A lot worse. Tell me, do all members of the vigiles carry identity tags?'

He stared, then took from a pouch on his belt a small bone counter, exactly like the one from Ostia. He let me examine it. On the face was the symbol COH IV, surrounded by ROMA and PREF VIG. On the reverse, being a neat, systematic character, Petro had scratched in full his three names.

`You don't wear it?'

`Some do. I don't like cords around my neck – villains can grab at them and throttle you.' Well he was right about that.

I gave him back his tag. Then I took from my tunic the other disc, handing it over in silence. By then he was expecting sorrow… His face had set into melancholy hollows. He turned the bone and read the name: LINUS.

Petronius sat on one of the delicate couches, leaning forwards, knees apart, hands clasped between them, holding the disc. I told him what had happened, as far as the customs force had worked it out. When I finished I walked over to a folding door and stood staring out at a garden while Petro absorbed the facts and tried to cope.

`This is my fault.'

I had known he would say that. It was nobody's fault, but taking the blame was the only way Petronius could handle his grief. `You know that's wrong.'

`How can get them, Falco?'

`I don't know. Look, we can't even start yet; there have to be formalities. Rubella is going to write a letter of sympathy to the relations, but you know what that will sound like.' We had both seen how officialdom informs bereaved families of death.

`Oh dear gods! That isn't any good.' Petronius roused himself. `I'll have to go. I'll have to tell his wife.'

`I'll come with you,' I said. I hardly knew Linus, but I had met him once and even the brief memory affected me. I was involved.

Petro made no move yet. He was still struggling. `I'm trying not to think about what this means.'

He spoke the name on the tablet he was cradling so gently. Linus. Linus, the young, keen undercover man whom Petro had placed on the ship that had supposedly taken the condemned criminal Balbinus into exile.

The death of Linus at Ostia must strongly imply that Balbinus Pius never went. In reality the ship must have dropped off passengers at the harbour mouth. Either then, or very shortly afterwards, Petro's agent was dead:

IL

NORMALLY I LIKED widows. They are women of the world, often without guardians, and frequently adventurous. This one was different. She did not know she was a widow yet.

Her name was Rufina. She admitted us both with a hint of a simper, then offered us wine, which we refused.

`Greetings, chief!'

Rufina looked about thirty-five, at any rate older than Linus. She dressed smartly, though her jewellery consisted merely of coloured beads strung on wires. There was no spare meat on her. She was not as pretty as she tried to act. Her manner was brash and ingratiating in a way I could only just tolerate, given what I knew.

`This is about time, I must say. I hoped you would be dropping in sometime. He's famous for being conscientious,'. she giggled at me. I felt ill. She crossed her knees, showing ankles and toes beneath the hem of her gown. `Have you brought me news of my husband?' Things were already unbearable. She managed to make the reference to having a husband seem even more saucy than the previous comment about Petro calling on her while Linus was away.

Petronius closed his eyes briefly. `Yes.'

I glanced around. Linus and Rufina lived in a third-floor back-of-building apartment that appeared to have just two rooms. They had made no attempt to redecorate what came with their lease; the usual landlord's dirty plasterwork, ornamented with half-hearted scrolls of red carried out by a painter who had two patterns and could only do one of those properly. With relief I realised there was no evidence of children in the house.

The furniture was sparse. There was a loom in one corner. Rufina was a home-worker, though the state of the weaving with an untidy straggle of wools in a basket on the floor and loose loom weights scattered everywhere suggested she approached it lethargically. From a wall niche two household gods, the lares and penates, dominated the room. The dancing figures were in bronze with a very dark patina, rather heavier and more ornate than the rest of their owners' lifestyle called for.

`It's very naughty of you to take Linus from me for months, you know.'

Petronius said nothing.

Doubt fluttered across Rufina's face. `What are you telling me, chief?' She was a vigiles wife. She must have spent most of her married life half-prepared for an official visit of this kind.

When Petronius told her what had happened she screamed so loudly we heard doors of other apartments opening in the outside corridor. At first she pretended she would not believe it, then, amid racking sobs and wild exclamations, she launched into the vilification that Petronius had dreaded.

`You should never have made him do it!' `Linus volunteered.'

Rufina howled. `He was afraid of you!'

It seemed more likely he was afraid of his own home life. I could vaguely remember Linus suggesting he had wanted to leave Italy for some peace. It seemed to me things could have been worse. Still, in relationships small habits can soon multiply into monumental grievances. `He wanted the adventure,' Petronius told the wife patiently. I could see he was badly shaken by the violence of Rufina's hysteria. `He was eager to travel.' Not that he managed it.