Philadelphion had been receiving his rebuke with pinched lips. In some respects he looked like a schoolboy whose misdemeanours had caused many a teacher’s tantrum before. As the Director paused for breath, the Zoo Keeper’s handsome features flushed, however; I suspect because we were listening. ‘You may be on my shortlist -’ Philetus made no attempt to curb the nastiness in his tone -’but do remember, I can only recommend a man of unsullied principles!’

Whirled by his own moral superiority, Philetus flew from the Zoo Keeper’s office. He whipped up a breeze with his robe so angrily, a scroll on the desk began unrolling. Helena put out a slim hand and steadied it.

‘As you see,’ Philadelphion remarked to me, once the man had left, ‘I am formally forbidden to present Roxana to you at the zoo this morning!’

He assumed a slight smile, the kind that often means a patient man is thinking how dearly he would like to throttle the bastard who has been insulting him. How slowly he would draw out the death, and how much pain he would inflict . . .

I spoke gently: ’I gather senior members have to be above reproach?’

‘Senior members,’ grated Philadelphion, now letting all his resentment show, ‘can be fools, liars, cheats or buffoons - well, you have met my colleagues, Falco - but they must never reveal that they are having a more pleasant life than the Director.’

Helena’s chin was up. I flashed her a grin, including the Zoo Keeper. ‘So do what you like, but don’t let him find out?’

Philadelphion bridled. ‘The lady Roxana is intelligent, well-bred, well-read and a charming hostess.’ That sounded next best thing to a courtesan. When I met her she certainly came over as a game girl. The way she shot up that palm tree did the lass credit. I believed him that the sweet Roxana could discuss Socrates at the same time as serving a plate of fig fancies. I could imagine the rest of her talents too.

‘Philetus objects to your charming friend visiting you here?’ asked Helena, coolly.

‘She never does,’ Philadelphion said. ‘I see her at her house.’

‘But she came here last night?’

His face shadowed at the correction. He almost looked guilty. ‘Exceptionally.’

‘By appointment?’ I queried.

‘No. She must have had some reason to speak to me urgently’

‘You don’t know what?’ Helena took it up again. Philadelphion shook his head, as if she was a fly tormenting him.

My turn: ‘So where were you last night?’

He looked as if he was about to say something different, then: ‘In my office,’ he answered, so firmly it sounded unreliable. ‘Until I heard the commotion and came running.’

‘In your office - doing what?’ I pressed him.

‘Catching up on the zoo accounts.’ He indicated the scroll on his desk, which was indeed sitting next to an abacus. Cynically I wondered if the abacus had been placed there this morning deliberately. Helena picked up the scroll, as if unaware she was doing it; almost idly, she unravelled a little of the end, while I continued the questions.

‘Any idea what the young man Heras could have been doing in your zoo last night, Philadelphion?’

‘None. Maybe students came for pranks, but we found nothing.’

Young men’s pranks seemed to be the Museion’s excuse for anything unusual. ‘We met him. Heras did not seem one to lark about.’

‘I know very little about him,’ said Philadelphion. ‘He was not a science student. I understand he was in Alexandria to learn rhetoric, intending a public career. Someone said he came with you to the necropsy of Theon.’

‘He was friends with my young brother-in-law. Did he know Roxana?’

‘Not at all.’

‘You asked her?’ Helena put in. It made Philadelphion pause. When this pause lasted a long time, Helena altered tack: ’Well! Can we discuss the shortlist tor the post of Librarian? Many congratulations on being included - but the obvious questions are, how do you rate your own chances and how do you feel about your rivals?’

Philadelphion had previously been disposed to gossip; he did not fail us now: ’Zenon is the dark horse - who knows what Zenon thinks, or how he will perform? Philetus obviously wants to give the post to Apollophanes, but will even our Director be so brazen as to recommend his own satellite? You could see Philetus starting to try to manipulate the list when he talked to me just now. He was threatening me - looking for excuses to support another candidate.’

‘Marcus Didius and I were disappointed not to see Timosthenes given a chance.’

‘Not as disappointed as him. He took his omission very nastily’

‘What of Nicanor?’ Helena prompted.

‘Nicanor thinks himself well qualified.’

‘What do you think?’ She did not mention Nicanor’s offer to bribe me, in case he thought she was hinting.

‘A bully. Frankly, I shudder at the prospect of working with him.’

‘Someone suggested that Nicanor admires Roxana,’ Helena put forward quietly.

‘Many people who know her admire Roxana,’ Philadelphion snapped back tetchily.

Helena had a tricky expression. Quickly, I weighed in and returned to asking what Roxana had told her lover about the Sobek incident. His version ran: she had come to find him; on the way she heard odd noises; she bravely ventured to investigate and found Sobek killing and eating Heras. Roxana yelled, so the crocodile left the body; she realised the beast was about to attack her too, so she climbed the tree and shouted for help. Then I came along - ‘For which Roxana and I must thank you, Falco, most sincerely’

Helena purred that that was unnecessary; no doubt when we saw Roxana, she would thank me herself.

Chaereas was deputed to take us to Roxana’s house.

On the way there I asked Chaereas about last night and he told me the same stuff we had heard from Chaeteas. Exactly the same. He too blamed an uncharacteristic escape by Sobek. He too called the death of Heras an accident. He had no explanation for the goat.

‘Had you and your colleague perhaps used the meat to feed Sobek?’

‘Oh no,’ Chaereas assured us.

On arrival, he left us to go in by ourselves. Roxana had rooms in an anonymous building, up a dusty staircase, off an uninspiring street. This was typical of Alexandria. In Rome it would have told us she was a struggling manicurist, with five children by three fathers. Here, it meant nothing.

Inside was quite different. Discreet servants padded about a large apartment that was decorated with subtle, extremely feminine opulence. There were rugs everywhere; there were seats formed from enormous cushions; there was much gleaming copperware, ivory and elaborate small pieces of furniture carved from rare woods. I could not see any scroll boxes to confirm the claim of intellectual competence, but I was prepared to believe philosophy and plays were hidden away somewhere. Either Roxana had inherited money or she had had a rich husband - whether living or deceased; or a lover, or more than one, spent a lot on her. Helena was making an inventory scathingly.

Cleaned up, the Zoo Keeper’s ladyfriend looked like a Vestal Virgin’s younger sister. When she appeared (which took some time), Roxana wore discreet robes in dark colours, a plain hairstyle and little jewellery. She moved into the room in a quiet hum of unnerving perfume, but was otherwise not exotic. Mind you, she gave the impression she could make herself just about as exotic as anybody wanted, if she chose.

Helena Justina failed to warm to her. Somehow I expected that. Helena’s presence at my side clearly surprised the lady. I must be the first good-looking man who, on coming to see Roxana, brought his wife. Well, that just showed her what clean-living persons Roman husbands were. And how well supervised.

Roxana’s evidence about the Heras tragedy was as well thought out and organised as her appearance. She told us exactly the same story as Philadelphion. They corroborated one another as tightly as Chaereas and Chaeteas had done. Rarely can descriptions have been so mathematically co-ordinated. My instinct was not to waste much time here.