‘And excuse me for asking – I have to cover everything – do you ever take rope with you on your excursions?’

‘I don’t have nothing to do with rope, tribune. I have enough to carry, with lock-wagglers and carry-home sacks – assuming I was the kind of fellow to have such stuff in the line of business.’

‘Well, you may as well admit you do,’ Faustus reminded him. ‘You have confessed you went on this burglary, and that you are a practised house-breaker.’

‘I’m saying nothing!’ Roscius sounded panicky.

‘You have told us you were in a house where two murders of citizens and the third of a slave took place.’

‘I was given immunity!’ The crook’s eyes swivelled to me, hoping I would support this claim.

‘You were given no assurances,’ said Faustus heavily. ‘The only thing you can rely on is this: if I can identify the real killers as a result of your evidence, any assistance will be taken into account. You volunteered the information – which will count more in your favour than if it was extracted from you by any other means. Keep calm, place your faith in justice, and if you have nothing else to tell us, you can go.’

Roscius turned to me. ‘He’s a cool one!’ he adjudged.

‘Sits in a bath of snow for pleasure,’ I answered. ‘Bunk off quick, while he’s given you the chance.’

Rabirius Roscius rushed to an access door at the end of the terrace. We heard him stride up the ramp as he left the building.

In silence, Faustus and I walked slowly back inside through the folding doors to the main hall.

The curator appeared while we were staring at one another in astonishment and bafflement at what we had heard. This keeper, a grimy old man in a long tunic, went and turned on the cascade. It was a ploy to get money. Faustus tossed him a coin without comment, then the man slunk away again. After a few hiccups, the nymphaeum display surged into life. Sheets of water, slightly brackish at first, sluiced over the steps and vanished away through secret exit channels.

‘Do we believe him?’ Faustus asked, frowning slightly at the unsought entertainment. I felt cooler already, standing near the moving water, though I pulled in my skirts in case of splashes.

‘I think so. It’s a weird tale to invent. Roscius had no need to admit ever being in the house, not unless his story is genuine. Oh, and Tiberius, he seemed truly horrified by what he says he saw. I definitely accept his depiction of the crime scene.’ Faustus nodded, in one of his silent moods. He liked to absorb information at his own pace.

More used to making quick assessments, I blew out air, then ticked off questions that surged into my mind:

Where were the slaves while the robbers were poking about the apartment?