"But they did eventually pursue him."

"Yes, because Milo made a decision to finish what his men had already started, without his consent. Which was more dangerous to him, Clodius wounded, or Clodius dead? Wounded, Clodius could return to Rome, rally his forces, bring legal proceedings against Milo for attempted murder, end Milo's bid for the consulship. If Clodius was dead, Milo would be liable for murder, but at least Clodius's followers might be paralysed with confusion, and Clodius himself wouldn't be around to accuse him. Either way, Milo was facing the ruin of everything he'd worked for. That's another reason I can't believe that the incident was premeditated. To have murdered Clodius by poison or stealth would have been one thing, but to have done so in such a clumsy fashion could only hurt Milo in the end. I wonder if he thought of his namesake Milo of Croton in the forest, trying to split that giant log and getting his hands hopelessly trapped? Did he hear the howling of hungry wolves as he paced there on the Appian Way, fretting over what to do next? It should have been an occasion of triumph for Milo – the end of Clodius, once and for all, within his grasp – but I think it must have been a very miserable moment for him."

"But he finally decided to send his men after Clodius," said Eco. "Once you've wounded a dangerous beast, it's always best to kill it. No doubt it's what Milo of Croton would have done."

"So he dispatched his men, then waited for news. Rather cowardly of him, not to join the battle himself."

"If you asked him, I imagine he'd say he hung back to stand guard over his wife and household."

Eco snorted derisively, then his face became shadowed. I had said the words sarcastically, but as soon as they were out of my mouth, it was hard not to think of our own loved ones and how vulnerable they were without us.

"Anyway," I said, "not too much later, along comes Senator Tedius and his daughter in their litter, with their own retinue of household slaves and bodyguards. Tedius and Milo recognize one another. Milo tells an outright lie – that he was set upon by bandits – and advises Tedius to turn back. The stubborn old senator instead presses on, despite some demurral on the part of his pious daughter.

"Meanwhile, down in Bovillae, the battle is joined. The innkeeper's wife – whose evidence we have secondhand from her sister – actually sees Eudamus and Birria kill one of Clodius's men on their approach to the inn. There's a terrific assault which destroys all the shutters and doors on the lower floor. The innkeeper is killed, along with Clodius's defenders. Clodius somehow ends up out in the road. We presume that Eudamus and Birria take his gold ring as a trophy, and to deliver proof of his death to their master. And then, for some reason, Eudamus and Birria and their men vanish, for when Tedius arrives a little later, the battle is over and the victors are gone. Tedius finds the inn a shambles. He sees blood and bodies scattered all about, including that of Clodius. The innkeeper's wife emerges from hiding on the upper floor. She looks out the window to see Tedius and his daughter leaning over Clodius. She goes downstairs, discovers her dead husband and loses her senses.

Tedius, despite his dislike of the man and his politics, does the honourable thing and loads Clodius into his litter, then sends the body on to Rome. He still thinks all the killing is the work of bandits, and decides to return to Aricia on foot. He turns about and trudges up the hill. While he stops to rest close to the House of the Vestals, Eudamus andBirria appear on the road and pass him, returning to Milo. How was it that he didn't see them before? Eudamus and Birria have prisoners. Felicia, peering out from the shrine of the Good Goddess, also sees these prisoners. Who are they? Not any of Clodius's men; the ones who fled with Clodius were all killed, and Fulvia told me that none of her husband's men were unaccounted for. So where did Eudamus and Birria come from and who were their prisoners?

"The gladiators return to Milo and deliver Clodius's ring, proof that he's dead. Milo then hands it over to Fausta, who proceeds down the road to make her offering at the House of the Vestals. But somehow Sextus Tedius never sees her. And when Tedius finishes his rest and moves on, by the time he reaches the shrine of the Good Goddess, Milo and all his company are gone.

"We know that Milo and the gladiators headed for the villa, where they killed the foreman and Halicor the tutor when they weren't able to find young Publius Clodius. Why was Milo seeking the boy? Is he really so spiteful and bloodthirsty that he wanted to murder Clodius's son? Or did he intend to somehow use the boy as a hostage? And how did he know that young Publius was staying at the villa?

"These are the questions, then, for which we have no answers." I picked up Eco's marking stick and for each question scraped a numeral in the wall.

"One: Where were Eudamus and Birria when Sextus Tedius arrived at the inn?

"Two: Who were the prisoners Eudamus and Birria herded up the road?

"Three: How did Fausta return down the road to make her offering at the House of the Vestals without passing Sextus Tedius?

"Four: When Milo forced his way into Clodius's villa, he demanded of Halicor and the foreman, 'Where is Publius Clodius?' – but how did he know the boy was at the villa, and what did he intend to do with him?"

I stood back and studied the marks -1, II, III, IV. They elucidated nothing. The longer I looked at them, the more they began to appear to be only an assemblage of upright and slanted lines signifying nothing, not even the numbers in my head. They were random lines etched by an idiot. For one brief, shuddering instant I thought I must truly have gone mad. The captivity, the darkness, the stench, the nightmares and the rats all coalesced like a black fog around my head. Nothing made sense; nothing was real. The whole drama of the murder on the Appian Way was only an elaborate fantasy I had contrived to amuse myself, a madman's epic. Milo and Clodius were figments of my imagination. Nothing existed but the pit.

"Papa? Are you all right?"

"What?"

"Your hand's shaking. You dropped the stick." Eco stooped and retrieved it for me.

His voice returned me to the moment. I clutched the stick in my hand, more firmly than I needed to. I reached out and slowly scraped another numeral into the wall, keeping my hand and my voice as steady as I could. "And now the more immediate questions, which surely must be related in some way to the first four.

"Five: Who waylaid us upon our return to Rome? We can be sure, I think, that they were not common kidnappers, looking for a ransom. They'd have wanted me to write something on a scrap of parchment, to prove I was alive. And they'd have figured out by now that there's no ransom to be had. We'd already be dead." The numerals on the wall began to lose their meaning again and I looked away, at the dank mound where Eco had buried the newest rat that morning. "Unless we're dead already."

"Of course they're not common kidnappers," Eco said, pretending not to hear my muttering. "They acted for someone who didn't like what we were up to on the Appian Way."

"More precisely, someone who was afraid of the information we might be bringing back to Rome. Therefore, six: To whom did we make ourselves dangerous with our investigation on the Appian Way?"

"But isn't it obvious, Papa? Milo, of course. We know he lied outrageously at Caelius's contio, with that tale about an ambush, and we know how to prove it. It's as you said to Felicia when you advised her to fly south – Milo is in a desperate situation, willing to commit desperate acts."

"Which leads us to the final question." I scraped the numeral VII into the wall. "Why were we kidnapped, not killed? If Milo – or whoever – merely wanted to dispose of us, why did his henchmen not murder us and steal our valuables, to make the incident look like another robbery by nameless bandits by the Monument of Basilius? If he wanted to ascertain what we had uncovered first, why were we not questioned, and then killed? Why did Milo not finish us off, as he finished off Clodius? Does he have some future use for us? I can't imagine what. It makes me wonder whether it was Milo who put us here after all."