'So what happened?' I managed to croak.

'The waiter seemed desperate for company. I suppose he was frightened to enter the murder room alone, even after he knew the body was no longer there. I was trying to think of an excuse to leave, without being rude to the poor man, when Petronius Longus arrived.'

I stared at him. He spoke to me at last. 'Encouraging your nicely bred girlfriend to visit the gory scene looks black, Falco.'

'Only if I'm guilty!' He must have known how closely I verged on losing my temper. 'And I did not send her.'

'A jury may not believe you,' Marponius commented.

'Juries are notoriously stupid! That's why the praetor will expect you to advise him on whether this charge is likely to stick before he lets things reach a court.'

'Oh I shall give the praetor good advice, Falco.'

'If justice is more than a dilettante hobby for you, your advice will be that this case stinks!'

'I don't think so.'

'Then you don't think-end of issue! I had no motive for killing the centurion.'

'He had a financial claim on you.' Without any formal signal, the atmosphere had shifted so that the judge was grilling me.

'No, he had a claim against my brother. But the claim was rocky. Marponius, I don't want to slander the brave centurions of the glorious Fifteenth Legion, but my private investigations already suggest it was a claim they could not pursue too openly. Anyway, where are your facts? Censorinus was seen alive, eating his dinner at the caupona, long after I had left and gone home to my own family. Petronius Longus has checked up on my movements the next day, and although there may be a period that I can't account for with witnesses, neither can you present anyone who will say they saw me at Flora's when the soldier lost his life.'

'The fact that you disagreed with him so violently-'

'Rules me out! We had a very strange quarrel, initiated by him, right in front of the very curious public. If you base your case on that, you are calling me a very stupid man.'

Marponius frowned. For a moment I had the illusion of controlling the situation, then the sensation altered. He made a gesture to Petronius. Some unpleasant challenge, previously arranged, was about to emerge.

Petronius Longus, with his air of misery deepening even further, stood up from his seat on the far side of the tasteful room and came across to me. He unwrapped a piece of cloth he had been guarding, and held out an object for me to inspect. He kept it just beyond my reach, and made sure that Marponius and Helena could both watch my face.

'Do you recognise this, Falco?'

I had a split second to reach the wrong decision. Delay would have answered for me. I took the honest option, like a fool. 'Yes,' I said. 'It appears to be one of my mother's cooking knives.'

Then Petronius Longus told me in a quiet voice, 'Helena Justina found it this morning amongst other utensils on the caupona's cooking bench.'

XXVIII

Criminals cut and run. For a second I knew why.

I stared at the knife. It was not one to excite a cutler. There was a gnarled bone handle, attached by a stout iron ring to a heavy blade that tapered to a solid point. The point had a small twist, as if at some time in its past the knife had been trapped and bent; such a nick at the end of a strong knife is impossible to straighten out.

It was like all my mother's other knives. They were not a true set, but they had all come from the Campagna when she was married. They were tough country items that she wielded with great force. Plenty of other homes in Rome must have similar gear. But I knew this was hers. Her initials were scratched on the handle: JT, for Junilla Tacita.

The room was quite large, but suddenly felt close and full of smoke from the braziers heating it. There were high square windows; I could hear a squall beating on the expensive glass, and one casement rattled. Squat slaves with straight-cut hair moved about constantly. Here was I, under threat of exile or far worse, while these ninnies came and went removing empty bowls and attending to the lamps. Helena dropped her hand back over mine; hers was icy cold.

Marponius was doing everything strictly now. 'Petronius Longus, have you shown this knife to Didius Falco's mother?'

'Yes, sir. She admits it must have been hers originally, but claims she lost this one at least twenty years ago.'

'How can she be sure?'

'She recognised the misshapen point.' Petro's quiet patience as he answered the judge's questions only depressed me more. 'She remembered it being caught in a cupboard door when her children were small.'

'Has she any explanation as to how it reached the caupona?'

'No, sir.'

'Describe how it was found.'

Petronius now had a set face. He gave his report with impeccable neutrality: 'I had ordered the removal of the body this afternoon. Later I entered the caupona with a view to completing my search of the scene. The soldier's corpse had been impeding a full investigation previously. I saw Helena Justina talking to the waiter at the foot of the stairs that run up from the kitchen to the rented rooms.'

'I remember!' said Marponius importantly.

'At my approach, Helena turned towards me, and appeared to notice this knife on the work bench; she picked it up. Both of us have eaten at Falco's mother's house on many occasions. We both recognised the pattern and initials. Helena made no attempt to hide it, but handed it to me immediately. As you see, it has been washed, but is stained around the shaft junction with traces of reddish colouring.'

'You take that to be blood?'

'I am afraid so.'

'What is your interpretation?'

Petro dragged out the words slowly. 'I asked the waiter about the knife. I didn't tell him I knew where it came from. He maintained he had never seen it before; it was not one he used at Flora's.'

'Is this the weapon which killed Censorinus?'

Petronius answered reluctantly. 'It may well be. If the waiter is telling the truth, the killer may have brought his own weapon to the caupona. When he came down from the bedroom he washed it in one of the buckets of water that are always in the kitchen area; then he threw the knife among the other utensils.'

'You're looking for someone intelligent,' I said dryly. 'It was a good place to hide a domestic implement. Pity it was recognised!'

Helena murmured in anguish, 'I'm sorry, Marcus. I just saw it and picked it up.'

I shrugged. 'That's all right. I never put it there.'

'You cannot prove that you didn't,' said the judge.

'And you cannot prove that I did!'

Helena demanded of Marponius, 'Are you really convinced that knowing someone had been stabbed upstairs, the waiter would not notice a strange knife among his tools?'

'Epimandos is pretty vague,' I said. Marponius looked unhappy, knowing it was bad practice to produce a slave in court. (Worse still if my pet theory was right and Epimandos was a runaway.)

Petronius agreed with me: 'He keeps a jumble of kitchen tools lying about at the back of the caupona. He's dreamy, untidy, and he was hysterical after the corpse's discovery. He could have missed anything.'

I was grateful for his help, but had to go on. 'Petronius, I still cannot accept unequivocally that this knife killed the centurion. Flora's is not renowned for hygienic practices; the red stains may not be blood at all, or if they are, it may be left from cutting up meat. What I'm saying is, you cannot actually prove that this is the murder knife.'

'No,' he replied levelly. 'But it's about the right size for the wounds.' It seemed too small, lying in his great hand. 'It's sharp enough,' he added. All my mother's knives were. They looked clumsy, but she used them a lot. They would slice through a cabbage stalk quite easily, taking any careless fingertip with them.