I guessed these were Libycus’ cronies. When I mentioned him, they let me in and sat me down politely on a stool that they brushed clean. They realised he was in big trouble. I made sure they knew that if he was innocent I might help him, so it would be good to assist me.

They were leatherworkers. Not tanners; the smell of hides in preparation is outlawed from city centre neighbourhoods. Leather was supplied to them. These men cut out and put together purses, belts and other fancy goods, punching them with patterns and creating tassels. They had this typical workroom unit, from which they could also make sales. Finished goods hung on strings all around. At the back, steps led up to a mezzanine level where they slept.

I had not expected to continue my enquiries at this time of night, but you take what fate offers. So I learned that with a background in common, Secundus and Myrinus had made friends with Libycus at the baths; knowing these premises were empty and suitable for their business, he passed on a tip. Since they moved in, if ever Aviola didn’t want him, Libycus popped along to see them. They confirmed his story of visiting their shop on the night of the murders.

‘When he left you, was that only because the hour was late – or had you heard a disturbance?’ They said Libycus left because he was nervous in case his master wanted him. Worn out, Secundus and Myrinus then fell into a dead sleep. According to them, they knew nothing about the tragedy until next morning.

Well, that was possible.

Myrinus went up to fetch Polycarpus for me. When the steward came down and let me into the apartment, he was perfectly respectful, went ahead and set out lamps. I suggested he ought to supply a key; he promised to attend to it next day.

‘Do you know those leatherworkers?’

‘They seem a couple of good boys.’

Polycarpus asked how I had got on with the fugitive slaves. I confined myself to saying ‘we held useful discussions’. The slaves were not the only people who could be tight-lipped.

I was pretty sure Polycarpus believed himself capable of winkling more out of me, but he was professional enough to drop the subject. Maybe he guessed that if he didn’t, I was professional enough to thump him. Also, if he showed too much curiosity, it might look significant.

‘Do you feel any great loyalty to the fugitive slaves, Polycarpus?’

‘Yes, I feel responsible for them, as their supervisor. We all belong to the same household – one where I was a slave myself once. It counts, Flavia Albia.’

As Aviola’s freedman, he was supposed to feel more loyalty to his master, but was that really the case? If the slaves were in trouble, how far would Polycarpus go to protect them? Would there ever be a situation where he took their part against his master?