The pious speeches by the senate fathers were kept as brief as possible. It was the usual flowery offer of thanks to the sponsor of the races, in this case Claudius himself. The Emperor tapped his feet impatiently as he tried to catch the eye of the speakers and then made a quick waving gesture with his hand to get them to move on swiftly. The crowd cheered each speech politely, and then, as the last speaker climbed down from the podium on the island, they craned their necks expectantly, all eyes riveted to the line of gates at the far end of the Great Circus.

There was a moment of hushed expectancy. Then a great fanfare of trumpets shrilled out and the gates swung inwards to reveal the dark tunnels leading back to the marshalling area. There was movement in the shadows, then the chariot teams burst out of the tunnels and on to the sand of the Great Circus. The crowd jumped up and screamed with excitement, and slowly the cheers resolved into rival chants in support of each team, or of vulgar denigration of the opposition. Most of the Praetorians, clearly, were supporters of the blues and bellowed out the name of Porcius as he drove his team past the imperial box and saluted Emperor Claudius.

'Bastard better lose,' Macro said softly. Then he glanced around nervously and drew a deep breath.'Come on, Porcius!'

Cato raised an eyebrow as he caught his friend's gaze. Macro shrugged.'Just keeping on side. No point in starting a fight.'

The chariot teams completed a circuit of the track and then drew up in a line abreast, just in front of the Emperor. The crews clustered round, making final adjustments to the horses' harnesses and applying a last handful of grease to the chariot axles. The charioteers checked their reins and made sure that the razor-sharp safety knives were secure in their scabbards. Each charioteer wore a short, sleeveless tunic in his team's colours, and the light screens that folded around their legs were also painted in the team colours.

Macro focused his attention on Nepos, a wiry man with a dark complexion. Nepos stood erect and still in his green tunic. Too still for Macro's liking, almost as if he was too terrified to move. Or maybe he simply had nerves of steel. He'd better had.

Once the preparations were complete the crews withdrew from the track and the charioteers took the strain on their reins, holding back their horse teams. The animals had been raised to run flat out and jostled each other nervously, muzzles flaring as their powerful flanks heaved.

For a moment Cato forgot everything that troubled him as he sat forward on the edge of his bench and stared at the four chariot teams, tensed up and ready to explode into action. The Emperor nodded to the race marshal and the latter stepped up on to the podium at the front of the imperial box. He carried a small flag, which he carefully unfurled and slowly raised up until his arm was erect. Every eye of the tens of thousands of people in the Circus was on him and there was not a sound except for the snorting of the horses. The marshal waited until the teams were as level as they could be. Then he snatched his hand down and the flag dropped with a rippling flutter. Instantly the crowd roared. The charioteers cracked their reins and the horses kicked up plumes of sand as they yanked the chariots forward and the race began.

Porcius, true to his reputation, somehow managed to coax an extra burst of strength from his team and they had nosed ahead in the first length. The blues were just clear of the other teams as the chariots swerved round the end of the island, throwing up sheets of sand as the body of each chariot skidded round, and passed temporarily out of sight. The cheering of the spectators around Cato subsided as they turned their eyes to the other end of the island, waiting in tense anticipation for the chariots to reappear. Sand sprayed up an instant before the first chariot swung into view and the Praetorians leaped up in delight, screaming out their support for Porcius. Right behind him was Nepos, and Macro only just managed to restrain his cry of delight that Nepos was still in close contention. With desperate flicks of the reins Nepos steered his team to the outside as they raced down the track towards the imperial box. Gradually he closed on Porcius, then began to edge up alongside the blues. Porcius saw the danger and, with a quick tug on the reins, moved out to head off his rival.

A howl of outrage burst out from the supporters of the greens and Macro balled his hands into tight fists, but kept his lips clamped tightly together. Beside him, Cato just felt sick as he saw the man carrying the fate of their last few coins desperately rein in, then abruptly swerve left, closer to the island. Porcius had misjudged his manoeuvre and now his horses missed a pace as their charioteer urged them back on course. But it was too late. Nepos, leaning over the front rail of his chariot, was cracking his reins furiously and crying out encouragement to his team. They surged forward, inside the blues, past them and into the lead. Cato felt a surge of joy burst through his veins, and fought not to let it show.

'Yessss!' Macro punched his fist into the air, then looked round anxiously. Some of the guardsmen were looking at him in surprise, but quickly turned their attention back to the race.

'Watch it,' Cato muttered. 'I get the feeling we're not amongst friends.'

Back on the track, Nepos raced ahead, and rounded the island, disappearing from view. An instant later the blues swerved round after him and were gone. Already a sizeable gap had opened up between the leaders and the other two teams, the reds and the yellows, who were battling it out, neck and neck, trying to close up on the leaders. Once more the cheering on this side of the Circus died down as the race continued on the far side of the island. Heads swivelled to the far end of the central island, everyone watching intently.

Not everyone.

Cato glanced down into the imperial box and saw that Narcissus was staring back in his direction. Their eyes met. Cato was sure of it. The Imperial Secretary was staring directly at him, and there was nothing Cato could do but pretend it wasn't happening, as if he was just some face in the crowd. Then Narcissus raised a hand and pointed his finger at Cato, then waved slowly, before turning back towards the track. Cato felt the cold chill of terror trickle down his spine. He had been seen and recognised and there would be no avoiding the Imperial Secretary now. Cato knew he was as good as dead. Narcissus had beckoned to one of the guards officers and was speaking animatedly into his ear. It could be about anything, Cato hoped desperately; they could be talking about somebody or something else. Then Narcissus turned and pointed towards him and the officer nodded, and moved towards the entrance of the imperial box.

Cato grabbed his friend's arm. 'We have to go! Now!'

'Are you mad?' Macro shook his hand off. 'What's left of our money's out there. We're not going anywhere. Not until the race is over.'

'But…' Cato's mind raced. There was no time to explain it to Macro. And Macro wouldn't budge. 'All right! I'm heading back to that tavern. Find me there, afterwards.' He rose, snatched up his helmet and hurried up the steps towards the exit.

Behind him, Macro stretched out a hand. 'Cato! Wait! Oh, sod you, then!'

Cato scrambled down the steep steps into the arched gallery that ran around the Circus, under the banked seating. From there a wider flight of steps led down into the street, and his nailed boots echoed sharply off the columns and curved ceiling of the gallery. Above the dulled noise of the crowd he thought he could hear more footsteps, more nailed boots and a shout. He ran down the steps, three at a time, risking an injury in his bid to escape the Circus before Narcissus' men could stop him. At the bottom of the stairs he emerged from the shadows of the building and saw that there were still plenty of people ambling along the wide thoroughfare that ran beside the Great Circus. Cato knew if he ran he was sure to stand out from the crowd. He drew a breath and then moved in amongst the passers-by, filtering diagonally away from the steps towards an opening in the line of shops opposite, where a small side street ran down towards the Forum. Behind him he heard the clattering of boots on the steps, but, with iron will, he forced himself not to turn and look, but to keep walking steadily towards the side street. As people crossed his path, or barged into him, Cato refused to meet their gaze and moved on, all the while waiting for a shout from behind that would mean his doom. At last he reached the street corner, and ducked down the narrow alley, pausing only briefly to glance back towards the Great Circus. Four guardsmen were standing a few steps above the street, scrutinising the crowd, but none of them was looking in his direction.