I watched them enter the brothel, greeting the girl on the door as if they knew her. They could have been clients, visitors to Rome who had had Plato's recommended by a friend. That was my assumption until I realised the girl had let them enter without money changing hands.

There was no doubt Lalage had customers who kept monthly accounts here. However, the kind of men who were so favoured would not be lowlifes from the waterfront, but trusted people like the Very Important Patrician who came with lictors in tow. Gaius and Phlosis were here in some other, very different, context. And from the doorkeeper's friendly attitude, even if they had got lost on the Hill, down here at Plato's the incompetent couple were regular visitors.

I wondered whether to follow them in. I was in the wrong condition for adventures tonight. I was tired. It had been a hectic week, packed with incident, and I knew my concentration was slipping. Besides, Plato's was a huge warren; nobody knew I had come here tonight, and if I went inside I had no idea what I would be going into.

The situation was far too dangerous. For once, discretion won.

LVI

I NEEDED HELP with this. I needed someone who would be tough if we ran into trouble, someone trained to carry out surveillance properly. If my hunch was correct, I had stumbled across something major. It would be hazardous. It needed the vigiles. The person I really should take this evidence to was Petronius Longus. Well, that was impossible.

I could ask Rubella. Pride – pride and the fact that if I was wrong I could be merely watching a couple of paltry sneak thieves enjoying themselves at a brothel – determined me to take this forwards unofficially.

There were practical problems. I did need a partner. I wanted to subject the brothel to all-day surveillance, with the possibility of tailing some of its visitors as they came and went. I wondered whether I could risk using one of my nephews. But with Tertulla still missing I knew all the young Didii were being marched to school in convoys and supervised by anxious mothers. There was no way I could cream one off without an angry rumpus flaring up. Besides, even I could see this work was too dangerous.

Still desperate, I faced the fact that if Petronius would not help me what I needed was one of his men. With luck, whoever I picked would not be the happy sneak who had betrayed Linus.

As chance had it, on my way back up the Aventine I ran into Fusculus. He would have been ideal. Fusculus was fascinated by the world of small-time criminals, an expert on specialist dodges. He would be full of ideas on why a set of cargo raiders from Ostia might have come to Rome. It was he himself who had inspired my belief that Gaius and Phlosis might have serious significance: I remembered that after my own close shave with the stolen boat at Portus, he had told me Balbinus Pius used to run a whole gang of craft-rig thieves along the wharves in Rome. Maybe these two

were part of his old network. Maybe it was Balbinus who had brought Gaius and Phlosis here. Maybe that meant the brothel was being used to run his empire now. It looked like that good old ruse, a cover joint.

When I fell into step beside him Fusculus growled, `Get lost, Falco!'

Presumably Petronius had been unable to confide in any of his men the fact that one of them was a traitor. He needed to identify the bad apple first. So I could not call on that to justify my role in working for their tribune. `Settle down. So Petro's told you all that I'm a management nark. He says I betrayed his friendship to spy on you – and naturally you simple souls all think that's terrible.'

`I don't want to know you, Falco.'

`What beats me, Fusculus, is how if you're all in the clear you can take the attitude that anyone trying to oppose corruption has to be your enemy.'

`You're poison.'

`Wrong. What you mean is, he's your chief, so even if he wants to play the silly ass you'll stick by him to protect your promotion chances. You would all do better starting a whip-round to buy Lucius Petronius a new brain.'

Fusculus told me to get lost again, and this time I did.

I felt sour. Nobody likes being hated.

Luckily there was one person left whom I could safely call upon. Someone sufficiently experienced for my purposes. Someone who was hated too.

I knew where he lived: back again on the opposite side of the Hill, by the Clivus Publicus. The Fates were enjoying themselves tonight. I marched my weary feet there again, and fortunately found that he was not yet out on night patrol. It was as I thought. Petro always took the busy first shift. He left the later, quieter one to Martinus his deputy.

It was late. I came to the point. I had been hoping to avoid telling him. all my suspicions, but I soon saw that the best plan was to throw the big idea at him: `How's the hunt for Balbinus going? Not well. Of course not; he's too clever. But I think I've got a lead. I'd take it to Petronius, but since he wants to play soft, I'll have to do the surveillance alone. Maybe once I can demonstrate how the Balbinus empire now operates undercover at Plato's, Petro will want to join in. Maybe I won't give him the chance. I could keep all the glory me and whoever shares my trouble…'

Martinus did not fail me. He was overjoyed at being asked to help. Well I knew why: he thought it was his great chance to do Petro down.

I told him what I had seen at Plato's, and what I reckoned we might see if we watched the place. `Does Rubella know about this, Falco?'

`I'm not at liberty -'

`Don't get pious! I know what that means.'

I considered for a moment. `He doesn't know, but we shall have to tell him. You can't go missing from the official team.'

`I'll see Rubella,' Martinus suggested. `If he goes along with this, he can fix it. He can say he's sending me to some other cohort. The chief won't be the least surprised. It's more or less traditional that as soon as you're stretched beyond endurance on a really major case, your best man gets filched to look for brooch thieves in some disgusting bath-house in another watch's patch.'

I had no doubt that the axiomatic secondment would be easy to arrange. Whether Martinus was the Fourth Cohort's `best man' could brook more argument. That didn't matter. The pompous self-satisfied article was good enough for what I wanted. Martinus would love to spend all day just sitting in a food stall waiting for nothing much to happen. As long as I could be in a different food stall at the opposite end of the alley, I didn't care how tedious he was.

When I finally made it back there for the second time that night, Fountain Court lay in complete darkness. No one there wasted lamp oil providing light for muggers and porch-crawlers to go about their dirty work. I steeled myself and trod quietly, keeping to the centre of the lane. As I walked past the bakery I thought I heard a shutter creak above my head. I looked up, but could see nothing. The apartment above the bakery, the one with half its floor missing, could hardly have been let and all the storeys above it were supposed to be even more derelict. Once beside the laundry I looked back again to make certain, but nothing moved.

Climbing the endless steps to my apartment I should have felt more confident. I was now on my own territory. That situation can be deadly dangerous. You relax. You assume the problems of night-time in Rome are over. You know too much to be really observant. Your ears stop listening for unnatural sounds. You can easily be rushed by some unexpected watcher who is lurking in the pitch dark halfway up the stairs.

But nobody attacked me. If anyone lay in hiding, I never noticed. I reached my own door, opened it stealthily, and soon stood indoors.