If he chucks a stone, he's done for," muttered Petronius. I'll have the little tyke It was a hot day along the waterfront at the mouth of the Tiber in Ostia. Petro and I had badly needed a drink. It was so hot we only made it to just outside the vigiles patrol house and into the first bar. This was a sad backtrack. Our principle had always been, Never go into the first bar you see because it is bound to be rubbish." For the past fifteen years or so, since we met in the queue to enlist for the legions, whenever we sought refreshment we had always strolled a good distance away from home and work, in case we were followed and found. Actually we had sat in numerous bars that were rubbish but not many that were full of associates we wanted to avoid and very few that our women knew about. Don't get me wrong. We two were pious Romans with traditional values. Of course we admired our colleagues and adored our womenfolk. Just like old Brutus, any orator could say of us that Marcus Didius Falco and Lucius Petronius Longus were honourable men. And yes; the orator would make that claim with an irony even the most stupid mob would understand… As you can see, in the heat I had drunk up too quickly. I was already rambling. Petronius, the experienced enquiry chief of the Fourth Cohort of vigiles in Rome, was a measured man. He had his large hand clamped around his wine-shop beaker but his heavy right arm was currently at rest on the warm boards of our pavement table while he enjoyed a long, slow descent into tipsiness. He was here after putting his name down for detached duty. It was a pleasant life, especially since the villain he was waiting for never turned up. I was here to look for someone else, though I had not told Petro. Ostia, the port for Rome, was vibrant but its vigiles patrol house was falling apart and the bar outside was terrible. The place was little more than a shack leaning against the patrol-house wall. After a fire, the vigiles rankers would block the side street as they crowded around with mugs of liquor, desperate to soothe their raw throats and usually just as desperate to complain about their officers. At present the street was almost empty, so we could squat on two low stools at a tiny table with our legs stuck out across the pavement. There were no other customers. The day shift were having a lie-down in the squad house, hoping that nobody set fire to an oily pan in a crowded apartment, or if they did that nobody sounded the alarm. Petro and I were discussing our work and our women. Being still capable of two things at once, Petronius Longus was also watching the boy. The little lad was too intent; he looked like trouble. A giggling group would be annoying enough. But if this loner did hurl a rock through the doorway of the patrol house, then shout abuse and run away, he would run straight into my old friend. Mind you, he was only about seven. Petronius would probably not break his arms or legs. After Petronius had narrowed his eyes and watched for a while, he carried on talking. So how's your billet, Falco?" He was teasing and I scoffed. I can see why you don't want to stay in it!" Petro had been assigned a room inside the Ostia patrol house. He refused to occupy it, but had loaned the grim cell to me this week. We two had had our fill of barracks life when we were in the Second Augusta, our legion in Britain. Even marching camps in that remote province had been better organised than this dump. Ostia was mainly a four-month assignment, on rotation among the seven Rome cohorts; the provision was constantly under review, and it showed. Off the Decumanus Maximus a short way inside the Rome Gate, the buildings had been thrown up in a hurry three decades ago when Claudius built his new harbour. He first brought some of the rough and ready urban cohorts to guard the spanking new warehouses. Fires in the granaries subsequently caused a rethink; they had upped the provision and replaced the urbans, who were general troops, with the more professional vigiles, who were specialist fire-fighters. Rome's vital corn supply ought to be safe with them, the people would be fed, the city would be free from riots, and everyone would love the Emperor, who had arranged it all. The same happened here as in Rome. whilst on fire watch, especially at night, the vigiles found themselves apprehending not just arsonists but every kind of criminal. Now they policed the port and kept an eye on the town. The Ostians were still trying to get used to it. Petronius, who knew how to run rings around his superiors, only got involved in day-to-day issues when it suited him. His special operation had no time limit, so he had brought his family with him. Nowadays Petro cohabited with my sister Maia, who had four children, and in Ostia he had a young daughter of his own with whom he wanted contact. To house them all he had managed to fiddle the loan of a mansion, borrowed from a very wealthy local contact of the vigiles. I had not yet worked out the angle there. But as a result, his unwanted room in the patrol house was mine. Lucky me.

This squadron coop has well outlived its usefulness," I grumbled.

It's too small, it's dark, it's cramped, plus it's full of bad memories of villains who have been dragged in through the gate and never seen again. The latrine stinks. There is no cook-house. Equipment is left all over the exercise yard because every detachment thinks if they are only here for four months they can leave it rotting there for the next group to tidy up."

Yes, and there's mould in a big cistern underground," Petronius agreed cheekily.

Oh thanks. Don't tell my mother you have stuck me above some stagnant sink."

I won't tell your mother," he promised, if you promise not to tell your wife." He was frightened of Helena Justina. Quite rightly. My high-rank sweetheart had much stricter morals than most senators' daughters and she knew how to express her views. Petronius faked a contrite look. Well, the room is rough and I'm sorry, Marcus. But you're not staying long, are you?"

Of course not, Lucius, old pal." I was lying. Lucius Petronius had welcomed me as if I had just come on a visit to see how he was. I was withholding news of my own commission in Ostia. Last year, when the Emperor sent me to Britain on some murky palace errands, Petro had followed me out there. Only by chance did I learn that he was the lead player in a serious hunt for a major gangster. It still rankled that he had kept quiet. Now I was paying him back. He drank his wine. Then he winced. I nodded. It was a filthy vintage. Without a word, Petronius stood up. I stayed put. He walked slowly over to the little lad, who was still motionless outside the gate. They were about five strides from me.

Hello, there." Petro sounded friendly enough. What are you up to?" The small boy had a thin body under a worn tunic. It was fairly clean, a muddy shade, a size too big for him, with one sleeve of a white undertunic showing. He did not look like a native of Ostia. It was impossible to tell his nationality, but the layers of clothes suggested Mediterranean; only crazies from the north strip off in the heat. He wore no belt, though he had beaten-up brown sandals with their straps curled by age. His hair was too long and there were dark circles under his eyes. But he had been fed. He was fit. His was the normal look of a lad from the artisan classes, maybe required to work hard at the family trade and then allowed to stay up far too late on long summer nights. He stared up at Petronius Longus. What the boy saw was a big man waiting silently with a friendly expression, someone who might throw a beanbag about in an alley with the local children. The boy seemed streetwise yet clearly unaware that this was an officer whose slam-bang interrogation methods were a legend. All vigiles are hard, but Petronius could persuade incorrigible criminals to bleat out damning evidence against their favourite brothers. He could make them do it even if the brothers were innocent, although mostly he did prefer confessions of real guilt.