‘Back to basics then. The cameo comes from Antium, Persicus is sending it to his mistress. The gem is in some unconvincing wadding, in a parcel, in a pannier. The young bridegroom sets off on the donkey, no doubt whistling a jaunty measure and thinking about enthusiastic sex. Then what happened at the necropolis?’ I ticked off possibilities: ‘Better consider it: did the courier steal the gem?’

‘No,’ said Quintus. ‘He wouldn’t commit suicide and stuff himself in a shallow grave.’

‘So was he robbed by somebody who knew what he was carrying? Did the carter himself set it up, even?’

‘If so, he was foolish to report his courier missing.’ Quintus again. ‘And why would he kill his man?’

‘As for someone else knowing,’ Petronius said, ‘Fusculus heard they were always very discreet when they had valuables to transport.’

‘Models of good practice?’

‘Fusculus said the carter swears the lad was tried and trusted. Could be relied on to avoid attracting notice.’

Aulus, who had been subdued since Albia had hysterics, recovered enough to add his thoughts: ‘So, did the young man just classically happen to be in the wrong place at the wrong moment? Was his murder random—though then his attackers found our exquisite cameo in his donkey pannier and thought it was their lucky day?’

‘That seems right,’ I agreed. ‘Being chosen by a cruising killer was an accident.’

‘Someone who looked harmless, stopped him,’ said Petro. ‘Excuse me, what’s the way to Clusium?—My pocket lodestone’s broken . . . I don’t suppose this time the lurer said, Do you want to look at my brother’s lovely spear collection?—but we’ll never know.’

Helena had calmed down. She tidied bowls into piles. ‘Now stop tiptoeing around the big question.’ We men sat quiet, our backs a little straighter, our faces grave. ‘How did someone in Anacrites’ house get their hands on the cameo?’

Petronius drained his water cup. ‘As far as the Seventh Cohort know, the donkey and its pannier disappeared. Suppose later, while Anacrites and his men were investigating, they found the donkey wandering?’

‘Not right,’ I said. ‘He let the Seventh carry on with routine enquiries. Unlike you and the Fourth, he has no beef with the Seventh. Anyway if, for once, he actually found evidence, he would have boasted about it.’

Helena scoffed too: ‘Even if his men had legitimately discovered the parcel, why did the cameo end up hidden in their luggage?’

‘Are his agents screwing Anacrites—pinching evidence to sell?’ Normally deadpan, Aulus looked cheery at the thought.

‘Has been known,’ Petro confirmed dourly. I knew the problem was endemic among the vigiles. House fires gave particular scope for pilfering from victims. ‘But Anacrites knew about the gem, didn’t he, Falco?’