The king looked at them as helplessly as a frightened child. “The air!” he groaned. “It is hot!” and then he held out his hand to the princess, and showed her a flake of soot on it, and he dumbly pointed to others that were falling about them.

“How did you discover it?” he asked, and Thorndyke saw that he was trying to appear calm.

“Mr.—this gentleman's friend has returned from banishment, and——”

“Returned! has the wall been destroyed?”

“No; he accidentally discovered the danger, and came in a flying-machine to warn you.”

“Where is he? bring him to me, quick!”

“But you will not ——”

He waved his hand impatiently. “Go; if Alpha is saved he shall be at liberty—if it is not, what does it matter?”

Thorndyke hastened away after Johnston, who, when he was told of the king's words, readily accompanied his friend to the presence of the ruler. They found him with his daughter still on the balcony.

“How did you discover this?” asked the king, turning to the American.