I explained to Veleda that one reason I had agreed to Helena's suggestion and let her come to my house was that I hoped to use this period before I handed her over to justice – whoops, took her back to the authorities – in an attempt to discover what had really happened at the Quadrumatus house. If she was innocent of beheading Scaeva, I proposed to clear her. She seemed less impressed by this handsome offer than I thought she should have been. Maybe when you are already indicted for the deaths of thousands of Roman soldiers, one more murder makes little difference on the charge sheet. 'I like to know the truth, V eleda.' 'I remember.' She should do. I had, after all, once trekked for days to ask her, amongst other things, about the fate of a kidnapped army legate. It was nearly ten years now since that man disappeared in Germany, but if ever relationships became too friendly with this woman, what happened to the legate ought to be remembered. Veleda had not killed him (in her version), nor even ordered his appalling death by drowning while trussed up and pressed under a hurdle in a bog. Still, the devoted tribes who followed her had thought a kidnapped Roman army commander was a suitable 'gift' to send to her. Whether they expected her to eat him, rape him, kill him herself, or keep him on a perch in a golden cage and teach him to tweet nursery rhymes had never been entirely clear, but it was certain that even if his fickle captors had not finished him off before he ever reached her, Veleda herself would have sacrificed the legate to her gods and stacked his bones in the kind of shoulder-high ossuary that I and my companions saw in the forest. That was what this woman now sitting quietly in my home had once been. Perhaps she still was. In fact, since she showed no sign of repentance, make that 'perhaps' a 'probably'.

'You told me that you did not kill Scaeva.' Five years ago Veleda had assured me she did not kill the legate either; she may have been lying. She certainly was responsible for his death, through firing up her followers' bloodlust. She could be lying about Scaeva. 'Do you know who did kill him? Or why?' 'No.' 'Were you there when he died?' 'No.' 'But you saw his severed head lying in the atrium pool?' Perhaps Veleda hesitated. Petronius certainly winced as he imagined it. 'I did not see the head, Falco.' At my irritated growl, Veleda added quickly, 'I never passed through the atrium that day; I left by way of a tradesmen's exit on the side of the house. But I knew that Scaeva's head was there. Ganna had seen it. She ran and told me.

This did not fit the facts Ganna had fed to me. I wondered if, in some way I had yet to discover, Ganna was trying to protect the priestess.

'So tell us,' Petronius leaned forward with his 'trust me' look. 'What exactly happened on that afternoon. Let's start with why your – maid, is she? -' 'Acolyte,' I said tersely. 'Oh nice! We'll start with why your acolyte was walking thorough the atrium, shall we?'

Veleda told him without arguing: 'I had some letters that 1 could not read.' That was good. Whatever mad, romantic pleas Justinus had made, Veleda had never been able to read them. Excellent. 'At first 1 did not want to read them -' Even better. This was too important for scoring points, but Petro did enjoy a smirk at me over the way she was confiding in him. 'I became so unhappy 1 changed my mind. The only person we could trust there was the man who had delivered the letters to me: Scaeva. 1 was constantly being watched – that terrible old woman who attended on Drusilla Gratiana -' 'Phryne.' 1 scored no points for sounding knowledgeable. 'Phryne, of course. Phryne had always made it clear she hated me. She knew every move 1 made. So Ganna was going to ask Scaeva what the letters said.' 'She never managed it?' asked Petro. Veleda shook her head. Now the story went that Ganna only made it as far as the atrium that afternoon; she saw the head, then raced back – with the letters to inform Veleda of the murder. They realised at once that blame would be piled on the priestess, so with no chance for further conversation, Veleda made her escape in the laundry cart.

'So why didn't the young lady go with you?' asked Petro, with what he probably imagined was a winning smile. Veleda's eyes were shadowed; 1 reckoned she felt patronised. 'We thought there would be an investigation.' 'There is an investigation. Didius Falco is conducting it now.' 'No, we thought there would be an investigation at the house, straight after the murder. Ganna says nothing ever happened.'

1 interrupted quietly to explain that Quadrumatus Labeo had refused to have investigators on the premises until the nine days of formal mourning for Scaeva had finished. 'What's he hiding?' Petronius asked me. 'Did it to "spare the distressed relatives further upset".' 'Beautiful! Didn't these relatives want to know who killed their boy?' 'You said it!' 'Ganna did not understand what Quadrumatus was doing.' Veleda showed no emotion at our angry exchange. 'She despaired of justice, so she made her escape too. But initially we hoped she would be able to exonerate me. Ganna stayed behind in order to tell the enquiry officer what she had seen.' Petronius Longus, practised as he was, managed not to sound starded. 'And what was that?' Veleda, equally intelligent, was clearly enjoying the suspense. 'Ganna had seen someone positioning the head in the pool.' Of course we demanded to know who it was. According to Veleda, Ganna had never told her.

Petronius could see no problem with this. We would go and ask Ganna to name the culprit. That was before I explained that Ganna had now been placed for safe keeping in the House of the Vestal Virgins, where no men are allowed. 'You've been there, Falco!' 'In the first place, as you so often tell me, I am an idiot. Then, it nearly got me executed. If anyone is breaking into the Vestals' House, dear Lucius, it's your turn.' He declined the offer. 'So what happened to the letters from Justinus?' I asked Veleda. 'I left them behind in my hurry. Maybe Ganna still has them.' We would probably have put Veleda through some even more intense questioning, but at that moment Helena came in. Our daughters were clinging to her skirts, ruining the fabric while they gave the priestess the hostile toddlers' silent stare treatment. Stooping and prising little hands free, Helena announced that Zosime had come to the house as promised, so she was taking Veleda away from us for a consultation in private. Julia and Favonia made a break for safety, and rushed across the room to me. Petronius casually captured Favonia as she tumbled over in her haste.

Just as the priestess reached the door, Petronius stopped her. He always favoured the routine where a witness was allowed to think they had been released, then he flung an extra question at them. As my daughter hid her face in his tunic then peeped at the priestess, Petro called out: 'So, Veleda, when Zosime took you out among the homeless, did you ever suspect she was harming them, not healing?' Veleda looked surprised, then denied it. Helena then shepherded her out.

I asked Petronius if there was a real suspicion that Zosime was behind the deaths of the vagrants. Ever cagey about vigiles business, he merely confirmed that he had the woman on a watch list.

I was glad that Helena was supervising the consultation here. I could not see Zosime as a killer – but if she was, I did not want her working any fatal magic on Veleda. Having Rome's famous prisoner die before the Triumph would be bad enough. Having her die at my house would finish my career.