The seventh month passed, and one morning at the beginning of the eighth there came two of the Khalifa's bodyguard to the prison, who talked with Idris. Idris advanced to the two prisoners.

"Verily God is good to you, you men from the bad world," he said. "You are to look upon the countenance of the Khalifa. How happy you should be!"

Trench and Feversham rose up from the ground in no very happy frame of mind. "What does he want with us? Is this the end?" The questions started up clear in both their minds. They followed the two guards out through the door and up the street towards the Khalifa's house.

"Does it mean death?" said Feversham.

Trench shrugged his shoulders and laughed sourly. "It is on the cards that Nebbi Khiddr has suggested something of the kind," he said.

They were led into the great parade-ground before the mosque, and thence into the Khalifa's house, where another white man sat in attendance upon the threshold. Within the Khalifa was seated upon an angareb, and a grey-bearded Greek stood beside him. The Khalifa remarked to them that they were both to be employed upon the manufacture of gunpowder, with which the armies of the Turks were shortly to be overwhelmed.

Feversham was on the point of disclaiming any knowledge of the process, but before he could open his lips he heard Trench declaring in fluent Arabic that there was nothing connected with gunpowder which he did not know about; and upon his words they were both told they were to be employed at the powder factory under the supervision of the Greek.

For that Greek both prisoners will entertain a regard to their dying day. There was in the world a true Samaritan. It was out of sheer pity, knowing the two men to be herded in the House of Stone, that he suggested to the Khalifa their employment, and the same pity taught him to cover the deficiencies of their knowledge.

"I know nothing whatever about the making of gunpowder except that crystals are used," said Trench. "But we shall leave the prison each day, and that is something, though we return each night. Who knows when a chance of escape may come?"

The powder factory lay in the northward part of the town, and on the bank of the Nile just beyond the limits of the great mud wall and at the back of the slave market. Every morning the two prisoners were let out from the prison door, they tramped along the river-bank on the outside of the town wall, and came into the powder factory past the storehouses of the Khalifa's bodyguard. Every evening they went back by the same road to the House of Stone. No guard was sent with them, since flight seemed impossible, and each journey that they made they looked anxiously for the man in the blue robe. But the months passed, and May brought with it the summer.