'You're both in this, Falco!' He had a sharp voice, its effect as subtle as dragging a sword across a ceramic plate.

I noticed that Petronius Longus was looking embarrassed. This depressed me. He rarely made a lot of noise, but he was perfectly capable of treating Marponius with the contempt he deserved. When Petro stayed quite so silent things must be bad.

I nodded to him as he picked up on my scrutiny. 'You owe my disreputable nephew Gaius a finder's fee But I want it on record that I came here voluntarily.' Petro's stare remained unhelpful. I tackled his glib superior. 'So what's going on, Marponius?'

'I am waiting for someone to appear as a spokesman for the lady.'

Women possess no judicial identities; they are not allowed to appear in court, but must have a male relation representing them.

'I'll do it. I act for her father.'

'A message has gone to the Senator,' Marponius fussed. Helena pursed her lips while even Petronius winced. I hoped Camillus Verus was missing at some unknown public baths.

'Falco will speak for me,' Helena said coldly, adding, 'if I must have a male mouthpiece!'

'I require your guardian,' Marponius corrected. He was a pedantic nuisance.

'We regard ourselves as married,' said Helena. I tried not to look like a husband who had just been told the household bills were three times what he thought.

The judge was shocked. I murmured, 'Socially, it's a future fixture in the calendar, though a man with your grasp of the Twelve Tables will appreciate that the mere agreement of two parties that a marriage exists brings the contract into effect-'

'Don't get clever, Falco!' Marponius knew the legal tables backwards, but rarely met women who broke the rules. He glanced at Petronius for help, though was obviously remembering he distrusted Petro's loyalties. 'What am I supposed to make of this?'

'I'm afraid it's true love,' Petronius pronounced, with the sombre air of a public works engineer reporting a cracked sewer in the vicinity.

I decided against upsetting the judge's middle-class ethics with further wit. He was more used to threats. 'Marponius, Helena Justina is an innocent party. Camillus is very public-spirited, but having his noble child wrongly arrested may offend his tolerance. Your best plan is to establish the facts before the Senator arrives, and greet him by restoring his daughter with a public apology.'

I could sense that the others present were sharing an awkward moment. Agitation flickered in the wondrous dark depths of Helena's eyes, and her grip on my hand felt tense. More was wrong here than I yet knew.

A slave came in and informed the judge that the messengers had failed to find Camillus Verus. People were still looking, but his current whereabouts were unknown. Good man. My future father-in-law (as it seemed best to regard him while we were pretending to be respectable) knew when to lie low in a ditch.

His sensible daughter forced herself to be gracious to the judge: 'Ask your questions. I do not object in principle to answering in the presence of Didius Falco, and that of Lucius Petronius Longus, who is a valued family friend. Ask me what you want. If they advise me to defer my response on a particular matter, we can stop until Father arrives.'

I loved her. She was hating herself for sounding so meek-and hating Marponius for swallowing the act. 'Alternatively,' I told him, 'we can all sit around a finger-bowl of honey cakes, and while we wait for her furious parent you can try to sell the lady thirteen scrolls on natural philosophy in a filigree library box.'

Helena boasted prosaically, 'If it's concerned with fiery particles, I think I've read that one.'

'Tread gently,' I teased Marponius. 'The watch captain has apprehended an educated girl!'

'I'll expect a rapid batch of injunctions!' he quipped wryly, taking a grip on himself. Marponius could be an objectionable prig-but he was no fool. If a man had any sense of humour at all, Helena was likely to bring out the best in him.

'Actually, it lets her out of the murder,' I smiled. 'She never gets into trouble; she's always curled up on all the cushions in the house, with her nose in a scroll:' As we joked, those eyes of hers were still sending me agonised messages. I was desperate to find out the cause. 'Sweetheart, perhaps the man you regard as your marriage partner can properly ask why you are sitting in a stranger's house with a distressed expression and somewhat lightly chaperoned?'

'This is a formal examination,' Marponius interrupted, stiffly reacting to the implied criticism. 'It is a private session of my court! The lady knows I am a judge attached to the permanent tribunal relating to the Cornelian Law against assassins and drug-making-'

'Poisons, knifings and patricide,' I interpreted for Helena. The special murder tribunal had been established by the dictator Sulla. After a hundred and fifty years it had signally failed to stamp out death in the streets, but at least killers were processed efficiently, which suited Rome. The praetor had a whole panel of locally elected judges he could call on to hear cases, but Marponius had set himself up as the expert. He enjoyed his duties. (He enjoyed the status.) When he took an interest in the early stages of a particular investigation, he could rely on being chosen for the hearing afterwards if the officers of the watch ever caught someone.

Now they had caught me. Helena's distress made me attack Marponius. 'Under that legislation is there not a penalty by fire and water for inciting a judge falsely to bring a capital charge?'

'That is correct.' He had replied too calmly. He was too sure of his ground. Trouble was licking its fangs at me. 'No charge has been brought yet.'

'Then why is the lady here?'

'A charge does seem likely.'

'On what accusation?'

Helena answered me herself. 'Acting as an accessory.'

'Oh cobnuts!' I looked across at Petronius. His eyes, which were brown, honest and always frank, told me to believe it. I turned back to Helena. 'What's happened today? I know you went to the Saepta and visited my father.' I felt annoyed at having to mention Geminus, but making Helena sound like a girl who devoted her attentions to the family seemed a good idea. 'Did something occur afterwards?'

'I was going home to your mother's house. On the way,' she said rather guiltily, 'I happened to pass Flora's Caupona.'

I was starting to worry. 'Carry on!'

'I saw the body of Censorinus being taken away. The street was blocked temporarily, so I had to wait. I was of course in a carrying-chair,' she inserted, having grasped that some niceties were called for. 'The bearers talked to the waiter from the caupona while we were stuck there, and he happened to be bewailing the fact that he now had to tidy up the rented room.'

'So?'

'So I offered to help.'

I let go of her hand and folded my arms. The bad memory of that bloody room where Censorinus was murdered forced itself back into my mind. I had to repel it. Petronius knew I had been there, which was damning enough; admitting it to Marponius would be my key to a jail cell. Sending my girlfriend looked like the act of a desperate man.

I knew why she had done it. She wanted to scour the place for evidence that might clear me. But any stranger would assume she had gone there to remove clues that would convict. Marponius was bound to think it. Even Petro would be failing in his duty if he ignored the possibility. His deep sense of unhappiness filled the room almost like an odour. I had never before been so conscious of putting our long friendship under strain.

'It was stupid,' Helena spoke crisply. 'I offered on the spur of the moment.' I sat dumbstruck, unable to ask if she had got as far as the ghastly scene upstairs. She looked so white it seemed probable. My throat closed helplessly. 'I only reached the downstairs kitchen,' she said, as if I had transmitted my agony. 'Then I realised my presence there could only make things appear worse for you.'