No shadow passed behind Mastama's eyes, yet I knew he would refuse to help us. His reply was smooth and meaningless. If he was diagnosing a splinter in your finger, he would be just as bland. I wouldn't trust this man to mop up vomit – not that he would. He thought himself well above that level of patient care.

'I am loath to ask his grieving relatives about him,' I joined in, speaking firmly. 'But since it appears that the priestess killed him, I need to investigate Scaeva, and any possible relationship he had with her. As he was your patient, you must have known him as well as anyone.' 'A delightful young man.' Such clichйs were what I would expect from a pomposity with goat's whiskers. 'Why did you attend him? What was his illness?' 'Sniffies and -' Mastama cleared his throat slightly – 'sore throats. He suffered badly from catarrh in winter.' 'Do you mind if I ask how you treated him?' 'Patient confidentiality -' 'He's dead, Mastama; he won't sue. Being run down and suffering from an extension of childhood illnesses does not usually constitute a family secret anyway.' It did not normally lead to decapitation either, but this was not the time for bedside wit; Mastama lacked any sense of humour. 'What did you do for him?' Mastama was clearly annoyed, but he merely said, 'These are seasonal disorders. Difficult to cure.' Helena leaned forward, a stylus poised over a note-tablet between her long fingers. 'I believe you belong to the dogmatic school?' Such a question, from a woman, surprised Mastama. 'We diagnose scientifically. We study the human body through research and theory.'

'Research? You approve of dissection of corpses?' Helena had raised a contentious subject. Mastama's expression immediately became veiled. 'Did you dissect Scaeva?' I nearly choked. I was supposed to be outspoken, but Helena could be outrageous. I wondered if she had gleaned this background knowledge from Zosime. Not necessarily: Helena was quite capable of rushing to a library, while I had been mooning at Flora's Caupona yesterday, and reading up the major schools of medical thought with a scroll in one hand while she tucked the children into bed. She was addressing the doctor with an expression full of reasonable sweetness, while she posed her brutal questions: 'I wondered if the family might have allowed an autopsy, since somebody had already begun the process…'

Mastarna looked savage. But again his tone stayed level: 'No, I did not carry out a post-mortem examination on Gratianus Scaeva. Nor did I seek to do so. Cutting up corpses is illegal, young woman. Apart from a short period, in Alexandria, it always has been.' He made Alexandria sound a pit of depravity. That would be news to the learned liberals at the world's greatest library.

I was pretty sure that Scythax, the Fourth Cohort's vigiles doctor, had more than once conducted anatomical research using the remains of dead criminals, but I rettained ttom saying so. When the criminals had been thrown to the lions, not much of their corpses remained for Scythax to play with anyway.

It was my turn to tackle a frog in my throat. 'Tell me, Mastarna: did you attend Veleda too? She's on the run, and it is important for me to gain some idea of her physical condition.'

'The woman was hysterical, in my opinion.' Mastarna sounded curt. I saw Helena bristling. Unaware of it, Mastarna carried on condemning himselЈ 'Hysterical in the medical sense. I diagnosed a classic case of "wandering womb" -' I had heard Helena raving against doctors who dismissed all female ills as neurotic, and she particularly loathed the Greek idea that women's organs moved around their bodies, causing a kind of suffocation and hence a hysteria that explained any female symptoms, whether piles or athlete's foot. Her set face was eloquent: to suggest that a woman with a headache has her womb between her ears proves that the doctor has decayed matter where his brain should be… 'The woman refused to succumb to an internal examination.' As Helena visualised Mastarna offering to subject Veleda to a vaginal groping, no doubt conducted with a crude expanding metal uterine probe, she took a deep angry breath I intervened quickly: 'I believe Veleda had asked for trepanation. Was it your suggestion?' 'Trepanation was not carried out.' 'Were you willing to do it?' Mastarna seemed evasive. 'It never came to surgery.' 'But you had discussed it with her?' 'Not in person. Trepanation is a tradition in German communities, I understand – though I cannot believe it is often successful among unskilled barbarians. Veleda had asked whether any of the doctors who attend the Quadrumatus family possessed the necessary knowledge. Cleander's discipline forbids surgery; he was unwilling to attend a barbarian in any case. Aedemon is less snobbish but follows a theory that all illness is caused by putrefaction and can be addressed with chants and amulets, with purges, astringents and laxatives…' Mastarna's lip curled in contempt. 'Carried out to excess, that can be more lethal than the knife. I do on occasion conduct drilling to relieve pressure in the head -' He paused. 'But not this time.' He seemed uncomfortable. Maybe he thought I would criticise him for considering dangerous surgery on a state prisoner. 'So what happened?' 'Another practitioner was called in.' 'Cleander recommended her? Zosime. Her methods sound much less radical than skull-boring.' 'So I believe.' 'Still, you and she had a disagreement about the appropriate treatment?'

Recovering his confidence, Mastarna passed off the quarrel with Zosime as unimportant. 'There can be many approaches to ill health. All or any of them may work. Zosime was trained by my colleague, Cleander. His regime and mine are antipathetical.'

'But Zosime was not permitted to attempt her gentle regime?' Helena said.

Mastarna seemed reluctant to admit this, unaware that Zosime had told Helena she had been given the hint to abandon Veleda's care. 'It was an issue between her and the patient. Then, of course, the lady from Germany removed herself altogether.'

'Patient choice,' I commented. It was clear from Mastarna's expression he thought that kind of licence was a bad thing. The thought crossed my mind that if Veleda had trusted Zosime and wanted to continue with her suggested gentle treatment, after her escape the priestess might have traced the female doctor to the Temple of.Жsculapius. When we left Mastarna, irritated by more unsatisfactory answers from that suppurating smoothie (Helena's definition), I considered making our way home via Tiber Island. It would have meant a detour. And I reasoned that if Zosime had been willing to own up to further contact with Veleda, she would have confessed it to Helena when she came to our house yesterday. So late that afternoon, I tracked down Clemens and the soldiers on search duty; I dispatched them to do a room-by-room search of the temple and its hospital buildings. If Veleda was there, they would recognise her – or I hoped they would. I had warned them always to be aware that she might have changed her appearance. They were not to manhandle women with the rough treatment I had seen the Praetorians using, but they were to check carefully for height and eye colour, neither of which could be altered.

They did not find her. As Helena pointed out, if she ever had been at the hospital after her escape, then as soon as questions started to be asked, she would have been moved elsewhere. It was generally thought that runaways who could demonstrate they were seeking refuge from brutality were helped to disappear. If the staff sympathised with Veleda's predicament, she could have been whisked off by the same escape route.

After the search, we let it lie. I had no evidence at this stage that would justify either leaning heavily on Zosime or threatening the administrators. It had been a busy, though mainly unproductive day. I was ready for a quiet night in, planning my next moves. This was where, on a normal enquiry, I would have welcomed a case consultation with one of the Camillus brothers. It would be a good ploy on a winter's night. We could have sat around a warm brazier munching almonds and apples, with a glass or two of table wine, and Helena would steer us towards sensible conclusions while we men tried to duck the issue…