"Unsafe. Yes." Petro continued to talk and plan in a far-too-level voice. "We'll be known to have a grudge. First suspects."

"There must have been local witnesses."

"You know the answer to that, Falco."

"Too scared to talk. So what? We lay a complaint against him?"

"No proof

"Visit him mob-handed?"

"Dangerous."

"Suggest that he desists?"

"He will deny responsibility."

"Also, he'll know he's had an effect." For a moment we were silent. Then I said, "We'll do nothing."

Petronius breathed slowly. He knew this was not capitulation. "No. Not yet."

"It may take a long time. We'll keep her safe. Keep her out of his sight. Let him think he has won, let him forget about it."

"Then-'

"Then one day there will be an opportunity." It was a fact. I was not emotional.

"True. There always is." He smiled faintly. He was probably thinking the same as me.

There had been a man in Britain, during the Rebellion, who betrayed the Second Augusta, our legion. What happened to that man afterwards was subject to a communal pact of silence. He died. Everyone knows that. The record says he fell on his own sword, as an officer does. Perhaps he did.

I rose to leave. I held out my hand. Petronius grasped it without speaking.

First thing next day, Helena went over to my father's house to find out what she could. Pa was hovering at home; he kept the children out of the way while Helena comforted my sister. Maia was still in shock and, despite her previous reticence, the story all came out.

After Maia had told Anacrites she no longer wanted to see him, he seemed to take it well. Then he kept reappearing on her doorstep as if nothing had happened. She never involved me because she immediately realised it would do no good. Maia was stuck.

He had hung around openly for a couple of months, then she started dodging him. He shadowed her more secretly. After the first few weeks he stopped approaching her. Nothing was said. But she knew he was there. He wanted her to know. She dreaded his presence all the time. The oppressive situation took over her life. He intended that. He wanted her to be frightened. Isolated with the problem, even my courageous sister became extremely scared.

Maia kept hoping someone else would catch his eye. There was no reason why not. Anacrites could be pleasant. He was tolerable to look at; he earned a good screw. He had prestige. He owned property. He could take a woman to elegant receptions and private dinner parties not that he had done so with Maia. Their relationship had been far more casual, just neighbourly. They never formally went about the world together. I don't believe they even went to bed. They never would do now, so his obsessiveness was pointless. Men who stalk victims cannot see that. This was Maia's predicament. She knew she would not shake Anacrites off. Yet she knew it was going nowhere. He had nothing to gain. But she had everything to lose.

Like many women in that situation, she tried enduring her torment alone. In the end, she actually went to his office at the Palace, where for two hours she had tried reasoning with him. I knew how dangerous that could have been, but being Maia she got away with it, apparently unscathed. She appealed to Anacrites' intelligence. Anacrites apologised. He promised to stop hounding her.

Next day, thugs violently trashed her house.

That night, talking grimly about our predicament with the spy, Petronius and I had sworn to be sensible. We would leave him alone. We would both be watchful and patient. We would 'do' Anacrites, together, when the time was right.

But I knew each of us was quite prepared, if a chance arose, to take separate steps to deal with this.

Helena knew it too. Maia herself was a quick-witted girl- but Helena's mind worked even faster. Those great dark eyes saw at once what was likely to happen, and how any move against Anacrites could rebound dangerously on us. I should have realised that while Petro and I were plotting men's action, Helena Justina was constructing deeper plans. With the quiet logic of a cautious, clever woman, her plans were designed to take as many as possible of the people she loved well out of the way of trouble.

it was at this dark moment and because of it- that Pa and I turned up that corpse his treasured builders had left behind.

Maia had gone to live on the Janiculan, swearing it was temporary (hating the whole of idea of moving in with our father). Her children were terrified; she herself was now desperate. Maia Favonia tried to give them all ordered lives. She stuck to normal mealtimes and bedtimes and since facilities were there, she insisted that her children were clean. Then little Rhea became hysterical every time she was led to the bath house. And eventually we smashed a hole through to the disgusting grave.

I knew what would happen.

As we recovered outside in the fresh air, Pa managed an aggravating prayer. "Well, thank you, Jove! You have given me a son in a useful profession Marcus, I rely on you to sort this." He did not need to tell me he had no intention of paying fees.

I stalked off, telling him to send for the vi giles so he just had a slave fetch Petronius. I watched my crony curiously to see how he would approach it. "Geminus, stick this one up your arse." Good lad! "It's no use asking me. The vi giles only deal with crud inside the city boundary. Call in the Urban Cohorts. Give those sleepy wastrels something that stinks."

"Oh come on, boys," whined Pa. "Don't wish the bloody Urbans on me…"

He had a point. I felt us weakening. The three Urban Cohorts were the inferior rump of the Praetorian Guard. In theory they had a remit to solve serious crimes within a hundred-mile radius of Rome but their expertise (I mean their lack of it) made us weep. The Urbans were a bandits' charter. Towns in the Campagna and Etruria that were seeking law and order quietly made their own arrangements. Most could produce some ambitious magistrate who wanted to gain fame by cleaning pickpockets off streets. If not, they had the sophisticated alternative: many bandits are available for hire as protection, often at quite reasonable rates.

Petronius relented slightly. "You'll have to dispose of the body, Geminus. You won't even get an undertaker to face this- I'll send up a man we use for clearing obscene remains. I warn you, he's not cheap."

"The bill belongs to Gloccus and Cotta, surely," I said. Then I had a rethink. "Unless this is Gloccus or Cotta,.." A pleasing idea.

None of us wanted to go close enough to check. In fact, I would not have been able to identify our two useless contractors anyway. They believed in site management from a distance; I had cursed them for months, yet never seen either face to face. Their workforce had been depressing enough: the usual string of inadequates called Tiberius or Septimus who never knew what day it was all irritating drips who had problems with hangovers, backaches, girlfriends and dying grandfathers. The two things that united the labour force were feeble excuses and a complete lack of building skills.

If you think I sound harsh, just you sign a contract for extending your workshop space or refurbishing your dining room. Then wait and see.

Pa did eventually report the corpse to the Prefect of the Urban Cohorts. They wandered out to his house and first tried their usual trick: since the victims and presumed suspects were Romans, Pa should pass the problem to the city vi giles Pa stamped on that idea, and Petronius was there to state the case with real authority. Authority was a new concept to the Urbans, who caved in and borrowed lights. Inspecting the burial after nightfall was a great help.

Acting as if they had never seen a corpse before, they took note of the fact that a man (even they could tell that) had croaked and been dumped under a new mosaic floor. Petronius steered them into working out that someone stove in his head with a building tool. "That might be a spade," he explained rudely. "Or a heavy pick, maybe." The Urbans nodded wisely.