I was embellishing because it made no difference. It all sounded so normal – yet even if this had been a ritual in the making, surely it never happened on the night the couple were killed, not while they were already lying dead on their bed.

Roscius was not my only source. Their description failed to fit what I had been told by that other witness: Fauna, who lived upstairs. She had told me of commotion, alarm, voices shouting, people running around with lamps. At what point did that happen? The slaves would not know about Fauna and her husband, standing on stools to look down at the courtyard.

‘So what is the sequence of events?’ I asked, suddenly addressing Phaedrus.

He jumped, but managed not to look shifty. ‘We had our meal and that is when the robbers must have come. We found the silver missing and the dead bodies afterwards. When we came out and went to tidy up quietly, like you said.’

I surveyed him, unimpressed. ‘According to you, the robbers never knew you were all in the oecus, and by the time you emerged, they had been and gone?’

‘Must have done.’

‘So what happened to the silver and who killed Aviola and Mucia?’

‘The robbers did both. Took the goods and murdered our master.’

‘Your word against theirs, Phaedrus.’

‘They are criminals and we are loyal slaves of a good master.’

I let Phaedrus think I had swallowed it. ‘So when they deny it, the robbers are lying? As Chrysodorus said to me earlier, “that is what professional criminals are bound to do”?’ All three slaves nodded hard. ‘Well then. You were invisible in the oecus, a place where nobody would ever expect slaves to be, so the robbers missed you. They must have crept around so surreptitiously, you never heard them. But Phaedrus, according to your version, there is one big flaw.’ The tall blond porter realised what I was going to say while I was still speaking; I saw it in his eyes. ‘What happened to your colleague, Nicostratus? When do you say he was attacked?’

Quick-witted Amaranta moved into the conversation smoothly. ‘He was not with us. We had saved some food for him. Phaedrus was going to relieve him after he had finished, then Nicostratus would come across for his bowl.’

Libycus took this up: ‘The robbers bashed him when they came in, exactly as we have always said. We all thought he was on duty at the front, and if he made any noise when the thieves got in, we never heard a sound.’

‘Just like you never heard a squeak from Aviola and Mucia – even while they were murdered right next door? One wall between you and that horrific crime – I shall have to check how substantial and soundproof it is! … Are you still saying, Phaedrus, that you found Nicostratus lying in the corridor, so that was when you discovered the crimes and raised the alarm?’