Gennadius and Eugenius took the path down to the sea walls, where a guard loyal to the Synaxis let them through, and then they walked north along the docks to a small Orthodox church. There were no tunnels that Gennadius knew of directly into the city, but this church would do. A tunnel in its crypt led to the basement beneath a monastery in the nearby settlement of Cosmidion, only some two hundred yards north of Constantinople along the Golden Horn. Gennadius and Eugenius entered the church and moved to the back of the sanctuary, where a staircase led down to the crypt. There, behind a row of stone sarcophagi, they located a trapdoor with a ladder leading downwards into the darkness. Eugenius took a torch from the wall and descended first. Gennadius followed, and when he reached the floor of the tunnel he found a man waiting for him, a man from the East, with a broad, smooth face and shaved head. He held a torch in one hand and a small birdcage containing a pigeon sat at his feet. Something about the way the man looked at Gennadius unnerved the monk.
'What has brought you here, stranger?' Gennadius asked. This was the beginning of the code that he and Halil had agreed upon.
'I come seeking wisdom,' the man replied in passable Greek. It was the correct response.
'So you are Isa,' Gennadius said. 'Do you have what I asked for?'
'I have brought the poison,' Isa confirmed. He took out a small leather pouch and handed it to Gennadius. Gennadius opened it and peered inside. It was filled with white powder.
'What is this?'
'A powerful poison, made from bitter almonds,' Isa explained. 'When inhaled, the powder is fatal. The assassin need only throw it near the sultan.'
'Then it will do perfectly,' Gennadius said, carefully closing the pouch.
'Good. The grand vizier wishes to make it clear that the city is not to fall until the sultan is dead. Those are the terms of the deal. If you fulfil them, then you shall have what you wish.'
'Tell Halil not to worry. The messenger who will bring the key to unlock the city and the assassin who will kill the sultan are one and the same,' Gennadius said. 'I will send him when the time is right, when the siege has grown old and the sultan is desperate enough to listen.'
'What you do is your concern. So long as you succeed, the less that Halil knows, the better. In the meantime, if you should need to communicate with Halil, you will come here.' Isa picked up the birdcage and handed it to Gennadius. 'Use this bird to contact Halil. No message is necessary. Simply release it, and it will fly to Halil. A messenger will meet you here the night that he receives the bird, just after sunset. He will ask you a question to determine your identity. The answer is 'Edirne'.'
'I understand,' Gennadius said. He was impressed. The bird was an elegant mechanism.
'Then we are done here,' Isa said and turned to go.
'God go with you, my son,' Gennadius called after the retreating figure.
'God abandoned me long ago,' the man said as he disappeared into the darkness. Halil sat alone in his luxurious tent, propped up by cushions and with a portable writing desk across his lap. He had been busy writing since early morning, letter after letter to nearby emirs and beys, in which he requested the delivery of food and other supplies. The sultan's army consumed enormous quantities, and even after months of preparation, they would not be able to stay in the field for much over a week without fresh supplies. It was Halil's task to acquire those supplies. The letters he wrote were, of course, a mere formality. If the lords refused to supply the sultan's army at a fair price, then troops would simply take the provisions.
As Halil started yet another letter, Isa stepped into his tent. 'Servants, leave us,' Halil said. 'Isa, you may sit.' He gestured to some cushions on the floor, but Isa remained standing. 'I had expected you back sooner. You delivered the poison and the bird?'
'The monk has them both, and he promises that the city will not fall until Mehmed is dead.'
'Did he say anything else about his plans?'
'No, only that the messenger who brings the secret to conquering Constantinople will also be the one who brings news of Mehmed's death.'
'A riddle then,' Halil said. 'And one best left unsolved. The less we know of Gennadius's actions the better. I have another task for you.'
Isa held up his hand, cutting the vizier off. 'I grow tired of serving as your messenger. You promised me the release of my family if I did as you asked, and I have done all that you asked and more, these three years past.' He pulled a small pouch from beneath his robes. 'I am done with this. Release my family, or I will kill you here and now.'
A trickle of sweat ran down Halil's spine. 'Do not be rash, Isa,' he said, managing to keep his voice steady. 'If you kill me, then your family will die. You know that. Do not throw their lives away when you are so close to winning their freedom. I have but one more task for you, and then your family will be free.'
Isa hesitated, then finally put the pouch back beneath his robes. 'What would you have me do?'
'Go back to Edirne and kill young Bayezid, the son of the sultan,' Halil told him. 'Make his death look natural, but do it quickly. He must die before this siege is through, before the death of Mehmed.'
'And if I do this, then my family will be freed?'
'When my men hear that Bayezid is dead, then they will turn your family over to you, and you will be well rewarded for your many services.'
'I do not want any more of your money, Halil, only my family,' Isa said. His hand went back to the pouch of poison. 'Do I have your word that they will be freed?'
'You have my word.'
'Very well. For your sake, you had best keep your promise,' Isa said and left the tent.
Halil watched him go. Isa's family was his weakness, and it would be his undoing. Halil placed the letter to the city of Chorlu aside and began a new one, this time in code, to his agents in Edirne. Constantine stood at his post at the Fifth Military Gate, near the middle of the Mesoteichion, and squinted against the early morning light as he watched the Turkish army form ranks in the distance. Dalmata stood beside him, and Notaras was not far off at the Blachernae wall. The siege was now ten days old, and not a cannon had fired, not an arrow had flown. While the men of the city waited on the walls day after day with increasing anxiety, the Turkish camp remained unnervingly quiet. Now, the Turkish army had finally sprung to life. Even though he dreaded the carnage to come, Constantine found himself looking forward to the release of the dreadful tension that had hung over the city.
On the far plain, the Turkish army had finished forming ranks. Flags waved over each regiment, identifying the origins of particular units. In the centre of the janissaries, directly across from Constantine, the flag of Mehmed — a white standard covered in ornate Turkish script — waved in the breeze. Horns sounded from the Turkish army, their loud call shattering the silence, and the regiments began to move, marching forward in step to the boom of drums, the clash of cymbals and the ringing of small bells held high on sticks. The sound of the approaching army was deafening after the long silence. 'Prepare to fight!' Constantine shouted over the din. He had no sooner spoken than another blast of horns sounded, and the Turkish army halted.
'What are they waiting for?' Constantine growled. 'Why don't they just attack and be done with it?'
'I do not think that they mean to attack just yet,' Dalmata said. 'Look, heralds.'