‘I am a Persian.’

‘You too, then.’

They vanished into the inner chamber.

Valens went to the door and picked up the sword of the dead guard.

The eunuch and the boy reappeared. The eunuch had a small wrapped bundle. The boy was clutching a toy lion. Both wore hooded travelling cloaks.

The first flickers of flame were snaking up one of the wall hangings.

The keys!

Which of the two dead guards was the one from outside?

Valens could not remember. He took the sets of keys from both their belts. Then, for good measure, heaved Naduk over and took his as well.

‘We need to go.’

When they reached the bottom of the winding stairs, luck was with Valens. The very first key he tried fitted, the tumblers clicked back, and the lock opened.

Swinging wide the door of the tower revealed a scene of chaos.

Thick smoke billowed around the courtyard. The sun had set, and the gloom of the evening was lit by lurid fires. Horses and men were milling and shouting. The stable block was on fire.

‘You took your time,’ Narses said.

The Persian was waiting at the foot of the outer steps. The shapes of other men and horses were around him.

‘Everyone here?’ Valens said.

‘Yes. Things went well with you?’

‘Never better. And I see you have been busy.’

‘Bad idea having the kitchens under the same roof as the hay stalls,’ Narses said.

‘Oddly, I think the tower might have caught fire too,’ Valens said. ‘Is the sentry still at the postern?’

‘Yes. Shall I deal with him now?’

‘Not in that way. Show him this seal stone, and tell him the zendanig has ordered him to open the gate.’

Narses moved off. Decimus led up two spare horses, and gave the boy and the eunuch a leg up.

As Valens swung into the saddle, he looked around the courtyard. Some of the garrison had formed a chain to pass buckets from the well. It was an enterprise doomed to failure.

‘The postern is open,’ Hairan said. ‘It is time we left.’

*

Before they crested the ridge that would take them out of sight of the castle, they reined in. As if by a prearranged compact, everyone looked back.

The castle was a couple of miles away, etched black against the night by the flames. The north wind lifted great gouts of fire from the tower. They went streaming off into the sky. The walls of the tower were of stone, and might stand, but the floors and rafters were wood. The buildings in the courtyard would be burnt to charred beams and ashes. Despite the strength of the conflagration, at this distance nothing could be heard.

For I know this thing well in my heart, and my mind knows it:

There will come a day when sacred Ilion shall perish.

The lines of Homer that Decimus recited were famous.