What's your name?" I heard him ask.

Zeno." The worst Zeno would suspect was an approach from a pervert. He looked the kind who knew to yell loudly and run.

I am Petronius. So what's up, Zeno?" Zeno said something, very quietly. Then Petro offered his hand and the boy took it. They walked over to me. I was already dropping coins on the table to pay for our wine. I had heard the boy's answer, and I knew what my friend would do.

Falco, Zeno says that his mummy won't wake up." Petronius hid his foreboding. Shall we go and see what has happened to her?" From long experience, he and I reckoned that we knew.

The boy led us, with Petronius still gripping his grubby little hand. We walked along the Decumanus Maximus. Ostia was a long habitation, so it had a long and very hot main street. As a major route for trade commodities, it was already packed with an endless line of carts jostling their way out of town, in order to arrive in Rome at sunset as the daily ban on wheeled vehicles ended. We were walking against the traffic. They were heading towards Victory Square and the Rome Gate. In our direction, far ahead and way beyond the Forum, lay the Marine Gate and the open sea. Roads to our left passed through mixed habitation towards the Laurentine Gate, the exit into the lovely countryside on which our forefather Aeneas set his sights. Short roads to the right led to the Tiber. It would be chock full of boats and ferries, bound for the markets and the great Emporium. Beyond the Tiber lay another road to Rome, which would also be jammed with laden transports, those too all trundling towards the Golden City on the Transtiberina side.

You're not from hereabouts," Petronius probed. So where is home, Zeno?" Zeno had been trained to look dumb or daft. Far away?" This time the child let himself nod. Did you come on a ship?" Too specific. Zeno relapsed into vagueness. Petrp glanced at me over Zeno's head, then stopped asking. Questions would be better when we had seen whether the unresponsive mother had been battered by her husband or lover or whether [less likely] she had just faded away in her sleep from some natural illness. We passed the Theatre. Opposite that tight-arsed Augustan edifice were various old monuments and guild assembly rooms. Then came a podium holding a neat row of four little temples, all elderly in style, just before the approach road to the massive granary built by Claudius. We stayed on the Decumanus to the end of that block. Then the boy turned right, facing the river. He stopped in front of what had once been a fortified gatehouse, when Ostia was much smaller and much, much older. This would have been the boundary wall of the original settlement. It probably dated back to the supposed founding of the port by Ancus Martius, one of the traditional Kings of Rome. They built to last in those ancient times, using massive square blocks. The stolid gate, made redundant when the town expanded, had now been redeveloped into shops. Above them were a couple of rooms let to visiting foreigners. Petronius left Zeno with me; he made a brief enquiry at one of the shops, then went up alone by an outside stair. I sat on the kerb alongside the child, who meekly squatted by me.

Who told you to come to the vigiles for help, Zeno?" I asked nonchalantly, as we pulled in our feet in front of a heavy cart full of marble blocks.

Lygon told me, If anyone ever doesn't wake up, the vigiles will want to know." Lygon instantly became a key suspect. Is he one of the family?"

My uncle." The child looked embarrassed. There are uncles and uncles. Some uncles are no relation, as children understand.

Where is he at the moment?"

Gone away on business."

When do you think he will come back?" Zeno shrugged. No surprises there. Petronius stuck his head out of a window on the top storey.

Come up here, Falco." He sounded annoyed, not like a man who had just found a domestic tragedy. You can bring the boy."

Sounds as if your mother is all right, Zeno." We went up. The gatehouse contained a warren of small rooms, all kept cool by its massive construction. Zeno lived in a cheap let, a single airless room with no amenities. The mother was unconscious on what passed for a bed. It was the only one; Zeno must either sleep with her or on the floor. She was from the scrag end of womanhood; we had suspected that. She was dressed, in several layers, a traveller who wore all her wardrobe, as a deterrent to theft. The folds of cloth were richer than I expected, though when sleeping it off she wore them in bedraggled swathes. Sprawled face up on the mattress, she looked sour and middle-aged, but I guessed she was much younger and had fallen pregnant with Zeno in her teens. That was the type of menage it was.

Uncle" Lygon would be her latest lover; we could guess what he was like. some scrounging swine who was now playing the big fellow in a wine shop by the port. Presumably they both liked a tipple. Zeno's mother had imbibed so much she had passed out cold. I guessed that was yesterday.

Drunk as a dog." Petronius [a cat man] closed her drooling mouth with his thumb. This was a gesture to spare her young son. He wiped his thumb on his tunic at thigh level, with an expression of weary distaste. Much of his working life had been spent among this sad level of society, and he despaired of it. Had the child been any older, that would have ended our interest. Instead, since my sister was only around the corner in the loaned house, Petro made me stay at the gatehouse while he fetched Maia to sit with the mother until she came round. We would look after Zeno. Maia was furious to be given this task, but she had children herself. We took Zeno to play with her brood; Petro and I claimed that both of us would need to supervise them. Cursing, Maia stayed behind. Two hours later the woman revived. Maia came home with a ripe black eye, cuffed Zeno around the ears, told him to go and keep his mama out of trouble, then made us feel guilty all that evening.

Your lush is called Pullia. The family come from Soli, wherever that is. There's a man no one ever sees much. Pullia is dumped on her own while he goes out and has his fun; she's bored, but she never leaves the apartment. The child roams the streets. A neighbour in the cushion shop told me."

That's more than I found out," Petro soothed her admiringly. I didn't even notice that it was a cushion shop!"

Eyesight qualifications don't apply to the vigiles? Drop the flattery." Maia and Petro were in love. Happiness had failed to soften the cut and thrust of their repartee. Maia distrusted men who tried to ingratiate themselves and Petro was finding out fast just what he had fallen for. They were made for each other, though that did not mean this relationship would last. Petronius had always sought out fair-haired women previously, apart from his ex-wife. Arria Silvia looked a little like Maia, who was dark and smart, with a fiery temper and a brisk manner even when nothing had offended her. My Helena reckoned Petro had married Silvia because Maia was married herself at the time and refused to look at him. I knew Petro, and I could not believe it, but I saw the similarity.

Do the tipsy family pay their rent?" he asked Maia, pretending he was only making conversation.

Find out for yourself," snarled Maia, as she prodded her battered cheekbone. She was my favourite sister. I made sure Petronius applied soothing liniment to her eye as soon as Maia calmed down enough for him to get near her. I wouldn't risk it myself. The feckless folk from Soli were a typical splash of colour in the hectic marine society of Ostia. The place was awash with temporary visitors from all ends of the Empire. Attached in some way to nautical trade, they stayed weeks or months, awaiting a cargo, awaiting a payment, awaiting a friend, awaiting a passage. Some found work, though mostly the locals had the jobs and clung on to them. Now that Pullia had had a meeting with officialdom, her little group would probably be up and off. I was off myself, back to the patrol house. I could have stayed to dinner. The moneybags who had lent Petro the house had left his slaves behind, in accordance with the hospitality rules of the rich. They served up regular meals of excellent quality, for which Petronius was not billed. The food is here, eat, don't let it go to waste!" the steward urged. No one needed to be told twice. It was not for me, however. I was hoping that Helena would arrive that evening. The patrol house was somewhere no well-brought-up young lady would want to find herself alone.