With a last wave to Iaia, the four of us set off.

From the Avernine woods we emerged onto the high, windy ridge overlooking Lake Lucrinus and Crassus's camp. The plain was dotted with great plumes of smoke that rose from spit-fires and ovens; a crowd must eat. Through the haze I saw the great bowl of the wooden arena filled with spectators who had come to gawk and thrill at the funeral games. No faces were discernible at such a distance, only the mottled colours of the spectators dressed in their brightest clothing to enjoy the holiday and the perfect weather of a crisp autumn day. I heard the clash of swords against shields. The vague, general murmur of the crowd rose to roaring shouts that must have been heard across the water in Puteoli.

'The gladiators must still be fighting,' I said, squinting and trying to make out what was happening within the ring.

'Alexandros has strong eyes,' said Olympias. 'What do you see?'

'Yes, gladiators,' he said, shielding his brow from the sun. 'There must have already been several matches; I see pools of blood on the sand. Now three matches are being staged at once; three Thracians against three Gauls.'

'How can you tell?' asked Olympias.

'By their arms. The Gauls carry long, curved shields and short swords; they wear torques about their necks and plumed helmets. The Thracians fight with round shields and long, curved daggers, and wear round helmets with no visor.'

'Spartacus is a Thracian,' I said. 'Crassus no doubt chose Thracians so the crowd could vent its anger against them. They can expect no mercy from the spectators if they fall.'

'A Gaul is down!' Alexandros said.

'Yes, I see.' I squinted through the haze.

'He's thrown his blade aside and lifts his forefinger, asking for mercy. He must have fought well; the spectators grant it – see how they pull out their handkerchiefs?' The arena was like a bowl filled with fluttering doves as the crowd waved their white handkerchiefs. The Thracian helped the Gaul to his feet and they walked towards the exit together.

'Now one of the Thracians falls! See the wound in his leg, how it pours blood onto the sand! He stabs the ground with his dagger and holds up his forefinger.' A resounding chorus of catcalls and boos rose from the arena, a noise so full of hatred and blood lust that it caused hackles to rise on my neck. Instead of waving handkerchiefs the crowd pointed upwards with clenched fists. The defeated Thracian leaned back on his elbows, exposing his naked chest. The Gaul dropped to one knee, gripped his short sword with both hands and plunged it into the Thracian's heart.

Olympias turned her face away. Eco watched in glum fascination. Alexandros still wore the look of stern resolution with which he had departed Cumae.

The triumphant Gaul walked once around the perimeter of the ring, holding his sword aloft and receiving the accolades of the crowd while his opponent's body was dragged to the exit, leaving a long smear of blood across the sand.

The remaining Thracian suddenly bolted and began to run from his opponent. The crowd laughed and jeered. The Gaul chased after him, but the Thracian outdistanced him, refusing to fight. There was a commotion in the stands, then a dozen or more attendants entered the ring, some carrying whips and others wielding long, smouldering irons, so hot that I could see the glow at their tips and the little plumes of smoke that trailed after them. They poked at the Thracian, searing his arms and legs, making him jerk and clutch himself with pain. They lashed him with the whips, driving him back toward his opponent.

Olympias gripped Alexandros's bare arm, sinking her nails into the flesh. 'This was a mistake!' she hissed. "These people are mad, all of them. There's nothing we can do!'

Alexandros wavered. He stared down at the sickening spectacle, his jaw clenched. He gripped the reins so tightly that his arms began to tremble.

In the arena the Thracian finally began to fight again, running towards the Gaul with a high, mad scream that rose above the murmur of the crowd. The Gaul was taken unawares and retreated, tripping over his own feet and falling on his backside. He recovered enough to protect himself with his shield, but the Thracian was relentless, banging his shield against the other's and stabbing again and again with his curved blade. The Gaul was wounded; he threw his blade aside and frantically waved his forefinger in the air, signalling for mercy.

Handkerchiefs and clenched fists filled the air, together with a thunderous roar. At last the fists began to outnumber the handkerchiefs, and the crowd began to stamp and chant: 'Kill him! Kill him! Kill him!'

Instead, the Thracian threw down his dagger and shield. The attendants came after him again with their whips and irons, lashing and poking him from all directions, compelling him to perform a hideous, spastic dance. At last he picked up his dagger. They drove him back toward the Gaul, who was already covered with blood from the wounds on his arms. The Gaul rolled onto his stomach and pressed his hands to his visor, steeling himself. The Thracian dropped to his knees and drove the dagger into the Gaul's back again and again in time with the chanting of the crowd: 'Kill him! Kill him! Kill him!'

The Thracian stood and held his bloody dagger aloft. He began to perform a strange parody of a victory strut, lifting his knees comically and rolling his head on his shoulders, mocking the crowd. A great chorus of hissing, catcalls, booing, and raucous laughter echoed up from the arena; within the walls the noise must have been deafening. The attendants came after the Thracian with their whips and pokers, but he seemed not to feel the pain and only grudgingly allowed them to drive him toward the exit and out of sight.

'Do you need to see more, Alexandros?' whispered Olympias hoarsely. 'These people will tear you apart before you can utter a word! Crassus is giving them exactly what they want – there is nothing you can do, nothing Gordianus or anyone can do, to stop it. Come back with me to Cumae!'

I saw the fear in his eyes. I cursed my own vanity. Why drag him before Crassus, when it could only result in another needless death? What sort of fool was I, to imagine that the proof of his own guilt could humble Marcus Crassus, or that mere truth could sway him from giving the crowd the bloody entertainment they craved? I was ready to send Alexandros and Olympias fleeing back to the sea cave when the trumpets began to blare from the arena below.

A gate beneath the stands opened. The slaves trudged into the arena. In their hands they carried objects made of wood.

'What is it?' I said, squinting. 'What is it they carry in their hands?'

'Little swords,' Alexandros whispered. 'Short wooden swords, such as gladiators use to practise. Training swords. Toys.'

The crowd was quiet. There were no boos or hissing. They watched with hushed curiosity, wondering why such a sorry rabble was being paraded before them and curious to see what sort of spectacle Crassus had devised.

Gathered outside the eastern rim of the arena, where the crowd could not yet see them, a contingent of soldiers had gathered. Their armour glinted in the sun. Among them I saw trumpeters and standard bearers. They began to gather into ranks, preparing for an entrance into the arena. I suddenly understood and felt sick at heart.

'Little Meto,' I whispered. 'Little Meto, with only a toy sword to defend himself…'

My eyes met those of Alexandros. 'We're too late,' I said. 'To take the path to the road, and the road down into the valley -' I shook my head. 'It will take too long.'

He bit his lip. 'Straight down the slope, then?'

'Too steep,' protested Olympias. 'The horses will stumble and break their necks!' But Alexandros and I were already ready bounding over the edge and racing down the steep hillside, with Eco a heartbeat behind.