At that moment a gust of wind whipped back the curtains and Macro had a clear view of the man Narcissus had been sitting next to in the imperial box. One of his arms was wrapped round a woman as he kissed her arched neck. His other hand was under the folds of her stola, between her legs, and her mouth gaped in ecstasy. They looked round sharply as the curtains flapped and their eyes met Macro’s for what seemed a long moment. Then as abruptly as it had come, the gust died and the curtains dropped back into place. Macro had not moved and the German called out another warning.

‘I’m going,’ he muttered before hurrying back inside the arena. A cold tremor of anxiety ran down his spine. The woman he had just seen in the throes of ecstasy was Agrippina. The last thing he wanted was to be a witness to the infidelity of the Empress. This was dangerous knowledge. Agrippina was sure to have learned from her predecessor’s mistakes and would realise the need to remove anyone who could denounce her to the Emperor.

Macro climbed the steps to rejoin Cato and sat down quickly, leaning back on his bench to make sure that he could not be seen from the imperial box.

‘What’s the matter with you?’ asked Cato. ‘You look as white as a toga.’

‘I’m fine … fine.’

‘What is it?’ Cato had rarely seen his friend look so worried.

Macro shook his head. ‘I can’t tell you now.’ He indicated the men sitting in front and on either side of them. ‘Not here.’

Down in the arena the first pair of gladiators had made their salute to the Emperor and now squared off, lowering themselves into a poised crouch as they waited for the signal to begin. The editor milked the tension for as long as he dared before shouting the command, ‘Engage!’

The smaller, more lithe of the two fighters charged in and launched a ferocious attack on his opponent and the sounds of blades clashing and the thud of sword strokes on shields echoed around the arena. Then both men parted and began to circle each other warily. Cato smiled at the small piece of theatre the gladiators had used to open the fight with a flash of excitement. Around them the Praetorians were avidly watching, muttering comments about the two gladiators’ physiques and fighting styles as they placed bets. Cato leant towards Macro and spoke as loudly as he dared.

‘It’s safe to speak now. Everyone’s concentrating on the action.’

Macro glanced round Cato to look into the imperial box. No more than thirty feet away the Empress had resumed her seat and was staring down into the arena, her face composed. The man who had been groping her was not in view. Macro quietly related what he had seen.

‘Are you sure they saw you clearly?’ asked Cato.