`I went to Ostia this morning,' Gaius said. That explained nothing. Yet somehow he managed to give his routine trip to work a resonant significance.

I sighed and gave up. Persuading Gaius Baebius to tell a five-minute tale normally took about three days…

I hung my cloak on a peg, flopped on the floor (since all the seats were taken), grabbed the baby from Junia and started playing with him and Nux.

`Marcus!' said Helena, in a light, warning voice.

`What's up?' I immediately stopped playing camels with the babe, though Nux had less sense and carried on pretending to hunt me like a wild boar. This dog would have to be put through a course on domestic etiquette. Maybe a better solution would be to get rid of the dog. (Maybe Gaius and Junia would like to foster her.)

`Marcus, Gaius Baebius has to visit an official. He wants to ask if you'll go with him.'

`Well, I just wondered if you could tell me the name,' Gaius demurred, as I was fending off the crazy dog.

`Whose name?'

`The tribune of the Fourth Cohort of the vigiles.'

`Marcus Rubella. He's a misery. Don't have anything to do with him.'

`I need to. The customs force have a report to make.'

`In full formal dress? What's up, Gaius? Is this something sensitive?'

On reflection it had to be, if those plodders in the taxation force had sent a supervisor back to Rome before the end of his shift. Gaius Baebius was also clearly disturbed by his task.

I stood up and straightened my tunic. I gave Junia the baby to hold again. Helena quietly squashed along a bench, leaving me room to perch on the end of it close to Gaius. That big wheat pudding was sitting on a stool, so he was lower than me. It made him vulnerable. to stern treatment. Gaius knew that. He was looking uncomfortable.

I tapped him on the knee and lowered my voice into friendly cajolement. `What's the game, Gaius?'

`It's a confidential matter.'

`You can tell me. Maybe I already know. Is it graft?'

He looked surprised. `No, nothing like that.'

`One of the inspectors made a nasty discovery,' interrupted Junia.

My sister Junia was an impatient, supercilious piece. She had a thin face, a skinny frame, and a washed-out character to match. She wound her black hair into tight plaits pinned around her head, with stiff little finger-long ringlets in front of her ears and either side of her neck. This was all modelled on a statue of Cleopatra: a big joke, believe me.

Life had disappointed Junia, and she was firmly convinced that it could not possibly be her own fault. In fact, between her terrible cooking and her resentful attitude, most of what went wrong could be easily explained.

She always treated her husband – in public anyway – as if supervising customs clerks stood on a par with the labours of Hercules, and was better paid. But his ponderous conversational style must drive her wild. Now she snorted and took charge of him: `An inspector in pursuit of unpaid harbour tax looked into a boat and found a dead man. The corpse was in a bad condition but it carried an identification tag. Gaius Baebius has been specially selected to bring it to Rome.' Junia spoke as if the trusty Gaius had flown here on winged sandals in a gilded helm.

My heart took an unpleasant lurch. `Show Marcus, Gaius,' Helena urged as if she had already managed to see it.

What he unwrapped cautiously from a piece of cloth was a simple bone disc. Gaius held it out to me on the cloth, reluctant to touch it. It looked clean. I picked it up between my fingertips. A nerve in my wrist gave an involuntary twitch.

It had a round hole at the top, through which were threaded two entwined leather strings. One of them was broken. The other still held in its knot. On one side of the disc were the letters COH IV. There were very neat, centrally set, with that telling gap which showed the last two letters were the numeral four. Around the rim in smaller letters was the word ROMA followed by a spacing mark, then PREF VIG. I turned the disc over. More untidily scratched on the back was one masculine name. It was a name I knew.

My face had set. `Where's the body, Gaius?'

Gaius must have recognised the dark tone in my voice. `They're bringing it from Ostia.' He cleared his throat. `We had a problem persuading a carter.'

I shook my head. I could work out how many days the body might have been lying at the, port. The filthy details I did not want to know.

It was clearly a matter of pride to have identified the disc and to be drawing official notice as promptly as possible. Customs like to think they are as sharp as fencing nails. Even so, my brother-in-law must have had mixed feelings even before he saw me. Officials stick together. A blow against one arm of the public service dismays them all. Always a lover of a crisis but aware of the implications, Gaius murmured, `Is this bad, Falco?'

`As bad as it could be.'

`What's happened?' demanded Junia.

I ignored her. `Was the man drowned, Gaius?'

`No. Thrown into the keel of an old barge that had been stuck on the silt for months. One of our lads noticed footprints on a mudbank, and thought he might have uncovered some smuggling. He had a bad fright. There were no hidden bales, just this: a corpse hidden out on the barge. Whoever dumped him probably thought no one would ever go out there to look.'

`You mean it made a safer hiding place than the ocean, which might have washed the corpse ashore?'

`Looked as if the fellow had been strangled, but it was hard to tell. Nobody wanted to touch the body. We had to, of course,' Gaius added hastily. `Once discovered it couldn't be left there.' Nice to know that in the customs realm the highest standards of public hygiene ruled.

`Was the disc actually on the corpse?'

Something in Gaius' manner made me wish I had not asked. He flushed slightly. Customs have their moments. Screwing money from reluctant importers they have to face plenty of aggravation, but it usually stops at shouting and obscenities. Holding back a shudder he confirmed the worst. `We spotted the thongs. I'm afraid the disc had been rammed in the poor fellow's mouth. It looked as if in the process of killing him, someone had tried to make him eat it.' I swallowed air. In my mind I was seeing a boyish, cheery face with bright eyes and an enthusiastic grin. Gaius enquired, `Is anyone missing?'

`No one the cohort knew was lost.'

`So was he one of theirs then?'

`Yes.' I was terse. I stood up again. `I knew him briefly. This is very important, Gaius – for the cohort and for Rome. I'll come with you to see Rubella.'

I refolded the cloth gently around its significant contents. Gaius put out his hand to take it back, but I closed my fist too fast for him.

We found- Marcus Rubella at the cohort headquarters. I was surprised. It was by then the hour when most people were thinking about relaxation and food. Mentally I had had Rubella listed as the type who worked set hours – the minimum he could get away with. I had imagined he would slide out with his oil flask and strigil, bidding his clerks farewell the minute the bathhouse stokers started thrusting wood into their stoves. I thought he probably left his work behind him then, and kept a clear mind all through dinner and his recreation hours.

But he was alone in the office, a still, brooding presence, staring at documents. When we first walked in he barely reacted. When I told him there was trouble he opened a shutter, as if to see the problem more clearly. For a brief moment he seemed the type who faced up to things after all.

Gaius Baebius relayed his story, prompted by me when he tried to slow down. Rubella made no fuss. Nor did he decide on any action, beyond some comment that he would write in sympathy to the family. Maybe he liked to brood first – or more likely he just loved to let events roll forwards without throwing in his own spear.