The scratching sound continued to come as the professor listened, and he got up and bent his head close to the wall. It sounded to him as though someone was scraping the rock wall on the other side of his cell, and he was puzzled over the circumstance. There was a measure of hope in the sound, perhaps the boys had arrived and were trying to break through to him. But as he continued to think it over he realized that it could not be so. The dungeon was deep in the earth and it would be impossible for them to get down on a level with his cell. The only other thing he could think of was that there was a prisoner in a cell next to his.
102

It might easily be possible that Sackett, in some of his other dishonest games, had taken someone else prisoner and the man was trying to break through to him. In that case it behooved the professor to try and help whoever was coming through the wall of his dungeon. He took the cigar lighter from his pocket, made it flash and then looked at his watch by its brief blue flame. It was now one o’clock in the morning.

Continuing to make flashes the teacher watched the wall and after a time found the rock upon which the unknown man was working. It was a large block in the very center of the south wall, and under the soft blows of the man on the other side it was already slightly loose. The professor could see it move. He took out a knife which he had and began to pick at the edges on his side, chipping carefully and as noiselessly as possible. It was evident that the person on the other side knew that he was helping for the scraping stopped abruptly but after a moment it was resumed.

They worked on in silence, the professor listening for sounds from upstairs, but none came. The men were evidently asleep or they had left the place altogether, for he heard no movement and he was not interrupted in his labors. He found that the soft and rotted material between the stones was easy to dislodge, and his mysterious helper was pushing as he worked, so that the huge stone was beginning to move toward the cell of the professor. Only a fraction of an inch at a time, but it was enough to give the teacher hope, and finally it was far enough out to allow him to get the tips of his fingers under the rough edge of the stone.
103

By working it back and forth the professor at length got it loose. It came out with a rush, nearly bending him double with the unexpected weight. At the same time a light flared in his eyes and he hastily deposited the stone on the floor of his dungeon. When this was completed he straightened up and confronted his companion.

It was Yappi, the mestizo. He held a torch of pitch wood in his one hand and a keen knife in the other. He had evidently worked hard at the stone, for his hands were dirty and so was his mouth and forehead, showing that he had stopped more than once to wipe them with his dirty hands. The professor was glad to see the man but more than astonished at what he saw back of him. The ranchman was standing in a vaulted underground passage, which ran back a distance that the professor could not make out.

“Yappi!” cried the professor, in a low voice. “How did you get here?”

“I followed you, senor,” said the old man, simply. “It was somewhat hard work, for my feet are not so swift to run as they once were. But when I knew that they had carried you off to this castle I laughed inside, for I knew this castle very well.”
104

In one sense Yappi was a mystery. He was an ordinary mixture of Spanish and Indian, and yet not ordinary in other ways. He possessed a dignity and his English was perfect. Ned Scott could never learn where he got it. Except for rare periods when he became sulky or falsely sensitive he was always steady and reliable. The professor had greatly misjudged him when he had thought him a coward, and later on apologized, an apology which was very graciously accepted.

“What is this underground passage?” whispered the professor eagerly, forgetting his situation in his interest.

“It is as old as the castle, senor, and I have known of it since I was a child. Many times I have played around these ruins. But come, we waste time and must be going.”

The opening that the removal of the stone had made was not a big one and the professor had a hard struggle to get out, in fact Yappi was compelled to haul him through bodily. Of a necessity the professor squirmed out and landed on his face, grumbling at the man who had made him resort to so clumsy a method of action. Once in the passage he looked around, finding that it was made of stone and arched overhead, the entire height being about seven feet. Consequently they were not compelled to bend over, and they hurried through the passage in comfort, the ranchman in the lead.

“What was this passage ever made for?” the professor asked.
105

“I do not know, senor. It may be that once that room was not a dungeon, or it may be—but who knows? Only I happened to know of the passage and knew that they would put you in that ce............