‘They need a guide,’ Marcia piped up before I could stop her, ‘to show them the way in the Pontine Marshes. That’s where they have to find the murderers, if those men go into hiding and think nobody will ever dare to go after them there since it is so horribly unhealthy.’

‘Thank you, Marcia,’ I replied coolly. She gave me her clever-little-girlie smile. I would have biffed her, but refused to be dragged down to her level.

Helena Justina, my companion in work and my soulmate in life, was now inspecting me as if I was one of the more repulsive insects from the fetid swamps under discussion. ‘O father of my children—’ She adjusted an ear-ring, an expressive punctuation. ‘Would that be the Pontine Marshes which have such a reputation for disease and death?’

I wiped my chin again as if I had missed a smear the first time. I placed the napkin on the serving table, neatly alongside my foodbowl; I straightened my spoon, rearranged my chewed olive stones in a more aesthetic pattern, then could no longer stall. ‘We may not have to go there.’

‘But if you do, Falco?’ Helena generally called me ‘Falco’ when I had let her down unspeakably—and had been so careless that she found out.

I had done my research. I spent the past couple of days in libraries—not what people generally expect of informers, but unless there is a good reason to hang around barmaids and Forum lags, I like to use reputable sources. The scrolls depressed me. ‘The good thing,’ I chirruped, ‘is that we are going in summer, when much of low-lying, scenic Old Latium dries out.’

Unfortunately, Helena was well read too. ‘Marcus, the modern theory is that drying out the land seasonally has only provided better summer breeding-grounds for flies!’

‘Olympus, is that what they say?’ I was genuinely glum.

A row of silver bangles jingled together on Helena’s left arm. ‘The flies are hideous. Even in the forests, clouds of them rise up at every step. The Pontine Marshes are so dangerous nobody will live there. What’s that proverb—You grow rich in a year, but you die in six months?’

Sometimes I liked having a partner who supplied me with background. At other moments I understood the men who married girls who had no time for arguments as they devoted themselves to athletes and actors. ‘I won’t be staying a year—not even six months.’

‘Six hours will be too long if the wrong fly bites you.’

‘Either we can pin the killings on our man, or we come straight home. In any case,’ I countered feebly, ‘as Marcia said, Petronius Longus is in charge of the logistics. He is bringing the best possible guardian—his own brother.’

My niece Marcia gave us a sniff that reminded me of my mother at her most disparaging. ‘Everyone thinks Petronius Rectus has gone off like a pint of bad prawns.’