I began to fret. Eco was no swimmer, and neither was the boy Meto, by his own admission. The idea of plunging into the water myself made me think of my ordeal of the other night; I tasted seawater in my throat and felt it burn my nostrils and experienced a tremor of panic. I looked at the scattered chorus of sailors' hats and the shadowy faces beneath them.

'You men!' I said at last. 'There must be a good swimmer among you! I'll pay any one of you five sesterces to take a look under the pier and tell me what's happened to the slave.'

There was a commotion among the scattered hats. Feet were drawn from the water, faces appeared, hands sought for balance.

'Hurry!' I shouted, looking into the bottomless green darkness and feeling a cold fear grip my throat. 'Hurry! Dive from where you are! Ten sesterces-'

But at that instant I was silenced by the bizarre apparition that emerged from the water at the end of the pier. The ferrymen froze in their places and stared as a long, gleaming blade soared straight upwards into the air. Wrapped in seaweed, the sword glittered silver and green beneath the sun. A long, white, muscular arm followed it, and then the broad shoulders and gasping face of Apollonius, smiling in triumph.

XVIII

Apollonius had compared himself to a dolphin – and indeed, lying naked on the pier with one arm slung over his face, his broad, clefted chest heaving for breath, his pale flesh wet and glistening, he looked to me like a young ocean god pulled from the deep. The planks all around him were dark with water, forming a rough outline of his body. Steam rose from his taut flesh, and rainbow-coloured beads glinted amid the ridges of his belly. Meto fetched his undertunic, which Apollonius dropped casually onto his lap.

Beside him, the sword shone in the sunlight. I knelt and plucked away the strands of seaweed. It had not been underwater for long; there were no traces of rust about the hilt. I knew little enough about the workmanship of such weapons, but from the decoration on the handle it appeared to be of Roman manufacture.

Apollonius sat up, crossed his legs and leaned back against his arms. He brushed one hand through his scalp and sent a spray of water through the air. A few drops caught Eco in the eye. He wiped his face and looked at Apollonius with an odd, sullen fascination, then averted his gaze. They were about the same age; I could imagine how intimidated Eco must feel in the presence of another male of such superb appearance, who could display his naked perfection without the least hint of awkwardness.

'This is not the only one?' I said, picking up the sword for a closer look.

'Far from it. There are whole bundles of them, lashed together with leather straps. I tried to bring up a bundle, but it was too heavy. The straps are all knotted and bloated with water, impossible to undo; I finally managed to rub one of the straps against a blade and cut through it.'

'Are swords all you saw?'

He shook his head. 'Spears, too, bundled the same way. And sacks full of something else. They were tied shut so that I couldn't see inside, and they were too heavy to lift.'

'I wonder what could be in those sacks,' I said, and felt a glimmer of intuition. 'How soon can you go down again?'

Apollonius shrugged, a gesture which upset the pools of water nestled in his collarbone and sent them streaming like quicksilver over his chest. 'I've caught my breath. But I could use a knife this time.'

The curious ferrymen kept their distance but had gathered close enough to overhear. One of them offered his knife, a strong blade fit for cutting leather straps, and Apollonius disappeared again beneath the water.

He was not gone long. This time he resurfaced headfirst, and when he pulled himself onto the pier it appeared that the knife was the only thing he carried. He stuck in into the wood, took his undertunic from Meto, then hurried towards the boathouse without a word. Meto ran after him. Eco and I followed. Apollonius's left hand, I noticed, was clenched tightly shut.

He walked around the boathouse and leaned against the wall, out of the ferrymen's sight. I approached him, tilting my head quizzically.

'Cup your hands together,' he whispered, 'like a bowl.' He extended his arm and opened his fist. The wet coins slithered into my hands like a school of tiny silver fish.

The same coins, having dried in the meantime, made a higher, more tinkling sound when I poured them onto the table in the library. Crassus had just returned from the funeral ceremony, still garbed in his black vestments and smelling of wood smoke. He raised a startled eyebrow. 'You found them where?'

'In the shallows just off the pier. The first night I arrived I saw someone dumping something from the dock. Whoever it was knocked me into the water and tried to drown me. He very nearly succeeded. It wasn't until today that I managed to send someone scavenging in the water. The slave Apollonius – yes, Mummius's favourite. This is what he found. Sacks and sacks full of silver, he says. And not just coins; there appear to be sacks full of gold and silver jewellery and trinkets as well. And weapons.'

'Weapons?'

'Bundles of swords and spears. Not gladiatorial or ceremonial weapons, but true soldier's weapons. I brought one of the swords to show you, but your guard confiscated it at the door. And speaking of guards, I'd suggest that you post several at the boathouse immediately. I left Eco and Apollonius to keep an eye on the ferrymen, but an armed guard will need to be set night and day until you can recover the whole cache.'

Crassus called to the guard outside the door and issued instructions, then had him bring in the sword that Apollonius had retrieved. From the open door came the noise of the funeral guests in the atrium. Crassus waited for the door to shut before he spoke.

'Curious,' he said. 'This was made at one of my own foundries here in Campania, from ore that came from one of my mines in Spain; you can see by this stamp on the pommel. How did it come to be here?'

'More to the point,' I said, 'where was it supposed to end up?'

'What do you mean?'

'If we assume that these things were being stored in the boathouse, and had been put there by Lucius Licinius, then what need did he have for so many weapons?'

'None.'

'Had he gathered them for your use?'

'If I had wanted Lucius to divert weapons from one of my foundries and to bring them here, I would have told him so,' said Crassus curdy.

'Then perhaps these weapons were being stored here for someone else. Who could possibly have a need for so many spears and swords?'

Crassus looked at me sternly, comprehending but unwilling to say the name aloud.

'Consider the valuables,' I went on, 'the coins and jewellery and metalwork all hoarded together in sacks like a pirate's booty. Assuming that Lucius didn't somehow steal it all, then perhaps it was delivered to him as payment.'

'Payment for what?'

'For something he himself didn't need but could obtain -weapons.'

Crassus looked at me, ashen-faced. 'You dare to suggest that my cousin Lucius was smuggling weapons to an enemy of Rome?'

'What else is a reasonable man to assume when he comes upon a hoard of weapons and valuables all lumped together in a hidden place? And the boathouse may not have been the only place where such things were stored in transit. The slave boy Meto mentioned to me that he sometimes saw swords and spears stored in the annexe behind the stables, the place where the slaves are now imprisoned. That annexe may have been empty of such wares when you arrived here, but that doesn't mean that it hasn't housed shipments of weapons in the past. And not only weapons; Meto also mentioned seeing stacks of shields and helmets. I hear that some of the Spartacans are reduced to wearing dried melon husks for helmets. Spartacus has a desperate need for well-made armour.'