“Too young to haf wisdom,” said Mustapha, with a gesture toward the boys.

“Come on, professor!” cried Dick. “If this dragoman will not act as guide for us, we can easily secure another.”

Instantly Mustapha hastened to assure them that he would be only too glad to act as their guide; but that they should pay him before visiting the Underground Palace, as they might never return, in which case he would lose his honestly earned due by neglecting to collect ahead.

They agreed to pay him in advance, and soon they set out from the hotel in Pera, eager to see the mysterious place that was said to hold so much of mystery and danger.

In the afternoon sunshine Stamboul was magnificent when seen from a distance. But when they had crossed the Golden Horn and plunged into the city all its impressiveness vanished. At intervals they came upon some splendid mosques, but mosques were far more impressive when seen from the proper distance.

Mustapha knew his business, and he conducted them to the place where they could descend and inspect the Underground Palace, but he declined to enter with them. For that purpose he called another man, with close-set, shifty eyes and a thin-lipped mouth.

“This dragoman, Bayazid,” he said. “He tak’ you.”

“Is he trustworthy?” asked the professor, with a slight show of nervousness.

“You not find one more so, effendi.”

So Bayazid, or “Pigeon,” as he was called in English, was engaged to show them the Underground Palace.