Above all the sprawling city was the citadel, the beating heart of the Kenyan empire, high on a hill. It didn’t crouch, squat and brooding, but soared upwards, vast ramparts of smooth stone above which peeked towers and roofs.

The emperor was behind those walls, controlling everything, sending out his spies. He had learned the pinnacle of statecraft: knowledge was power. Perhaps that was why he wanted the book that Wahir had tired of carrying and was now clutched by Said in his huge hands. Perhaps not.

To find out, they first had to pass the brazen doors. On either side of them were painted signs, repeating the same information in every conceivable language. Benzamir, master of the spoken word, searched for something he could read.

‘I’m having problems here,’ he said. ‘Said, can you read?’

Said, slack-mouthed and staring up at the citadel, shook himself. ‘I have to confess I never had to learn. In the madrasah we learned our letters and the Qur’an, but not the written word.’

‘Wahir?’

The boy was facing the other way, looking out over the Nairobi sprawl that went on and on until it merged with the sky.

‘Sorry, master.’

‘Can you read?’

‘If my teachers hadn’t beaten me with sticks, I might have. Is it important?’

People drifted between the signs until they found the one they could understand. There were no huge crowds, but most of those who stopped to read the signs seemed to come deliberately to read, and not to enter the citadel. Benzamir watched them: after they’d finished, they turned round and went back down the hill.

‘I’m rather assuming it is important. Otherwise why would they be there? Alessandra? Save the ignorant men from disaster.’

At last she seemed to have conquered her fear. ‘How would you manage without me?’ she said, and scanned the boards until she spotted one in the hand common to Misr.

‘If you read it out loud, I’ll be able to understand all the others,’ said Benzamir. ‘You’ll never have heard of the Rosetta Stone, but it’s the same principle.’

‘Please don’t explain. I’ll get a headache.’ Alessandra cleared her throat and read: ‘By order of His Imperial Majesty Kaisari Yohane Muzorewa and his lawful heirs and successors, no one may enter the imperial palace except with the express permission of His Imperial Majesty or his ministers. Anyone found within the palace without lawful authority will forfeit their lives. Subjects of His Imperial Majesty wishing to petition His Imperial Majesty on matters of law or state must obtain the permission of His Imperial Majesty or his ministers prior to the petition being presented.’ She coughed again. ‘This is all a bit of a mouthful, isn’t it?’

‘Does it say anything else?’

‘Hang on. Written by order of His Excellency Yusri Hakeem Misriyyun, representative of the City of Misr El Mahrosa. And some numbers: two thousand, nine hundred and seventy-eight. I don’t know what that means. They seem to be slightly different on all the others.’

‘It’s just the year,’ said Benzamir. ‘Right. The plan is this: we get some letters of introduction made up, written in my native language and Arabic. Then we find out how to get an invitation to an audience with His Imperial Majesty. We can present him with the book, and then . . .’

‘And then what, master?’ asked Said. ‘How do we ask him what he wants the book for without losing our heads?’

‘The emperor won’t tell us,’ said Alessandra. ‘He’ll just thank us for the book, pay us off and push us out of the door.’

‘He won’t have to tell us. I’ve bugged the book.’

‘How will insects help?’

‘Magic. These are special insects that no one can see but will tell me where the book is, what’s being said and even give me a picture of who’s holding it.’

‘Will your enemies be able to see these magic beetles?’ asked Wahir. ‘Is it like your tattoo?’

‘It’s a risk I have to take. I don’t think they’ll be watching for them, but even if they do detect the bugs, they won’t know for certain where they came from or who set them.’

Said nodded. ‘It’s a good plan then. We’ll need the best parchment, or vellum, and coloured inks.’ He looked through the purse and brought out the last of the sheikh’s money. ‘If this doesn’t work, we’re going to starve to death.’

‘To be honest,’ said Benzamir, ‘this is the bit that scares me most. Actually writing, using a pen or a brush, isn’t something I’m too familiar with. We have machines to write for us.’

Alessandra linked arms with him and started marching him down the hill to the riotous city below. ‘Then you’ll have to practise first, Benzamir. I’m not going hungry again.’

They rented a room in a house close by the citadel, with a wide window that let in lots of light. While Alessandra and Wahir went out to find inks and paint, paper and ribbon, Benzamir practised his Swahili on the landlady, and Said moved the single large table over to where it would be of most use.

Then they waited. It was becoming hot, and both men grew increasingly uncomfortable. They sat on the table, as close to the window as they could get without falling out, watching the street below slowly empty as the sun reached its zenith. All the time, the spires of the citadel winked and beckoned in the haze.

‘Look! A procession,’ said Said, and almost fell off the window ledge. ‘Merciful Allah! Is that an elephant?’

Benzamir craned his neck round the shutters and saw it was true. An elephant, dressed in heavy cloth sewn with thousands of metal plates, lumbered by. On its back was a small covered howdah carrying a driver and two archers. A handful of children had escaped their parents to watch from the street, and though they waved and called up, the soldiers imperiously ignored them.

Behind the elephant came a troop of spearmen, wearily trudging the dusty road, heads down; behind them, an ox cart pulled by a team of huge-horned cows, white with sweat and panting hard. Their load was an Arab driver, an ostrich-plumed Kenyan officer and three more people.

One was a prisoner. He had his hands chained together and around part of the cart to prevent his escape. He looked beaten, his dusty face pale next to his guard’s gleaming skin. The other two were of less certain position: they shared a ride with a captive man, yet they were free to grip the sides of the rolling cart on their own. One was a man, a Ewer most likely, with a hint of white-blond hair on his pink head and dressed all in black. The man’s clothing didn’t seem the most appropriate for the climate, and Benzamir wondered how far he was from home.

The woman . . . Benzamir felt his hands tighten around the windowsill and the breath catch in his throat. At that moment she happened to look up and saw them gawking down at her. She returned their curious stares with cool disregard.

Then they were past, heading up the hill towards the citadel.

‘Said?’ said Benzamir. ‘What story goes untold here?’

‘I’ll be back soon.’ Said slid off the table, and was gone. He reappeared trotting alongside the cart, asking questions of the driver. The officer shouted at him and tried to shoo him away, but Said was persistent. Only when he’d scavenged his answers did he stop, hands on his knees, gasping for breath. He trudged back.

‘You’re not going to believe this, master,’ he panted, and stopped to drink the water proffered by Benzamir. ‘The black man in chains is a thief. Guess what he stole?’

‘The emperor’s books? Did they get the other one back?’

‘No. The driver said that both had been lost, and the emperor was furious. The thief is going to be tried. And hanged. Or stoned. Or something like that.’

Benzamir refilled Said’s pottery mug. ‘Did the driver say when the trial was going to start?’

‘He said tomorrow. He said that the emperor himself was going to sit in judgement. The thief isn’t a common man, but one of the emperor’s underministers. I don’t know what that means, but it sounds important.’