"But who stole the box? Not Santiago, for he has not left his room for days. If it was Strong, he must have entered the bank from some direction other than this. I don't understand, but I'm going to make some further investigation."
He reëntered his room, buckled on his automatic and took from his suit case—which, by the way, he had located at the railway station along with that of his companions after the occupation of the city by the marines—his electric torch. Then he went out and descended the stairs, which he discovered were twenty-four in number.
Reaching the bottom he found himself upon a landing some six or eight feet square, from the opposite side of which another flight of stairs ascended.
"I reckon I better see where they lead to," was his comment as he slowly began their ascent.
After going up eighteen stairs his head touched the floor above. He counted the remaining steps by the light of his torch and found that there were six more. This would make the floor over his head on an exact level with the floor of Santiago's house.
"It's just as I expected," he muttered. "If I can get through this floor, I shall find myself in Don Esteban's residence—somewhere. But just where? That's the question."
He pushed upon the stone above his head, but it refused to move. Then he held up his torch and examined the ceiling carefully. Whatever the method by which the stones could be moved, it was carefully concealed.
Much chagrined, Billie at length decided to retrace his steps and await the coming of his companions. He reached the landing and crossed over to the steps by which he had descended.
Glancing up, he uttered an exclamation of surprise, for there at the opening and peering down the stairs was Ambrosio, the ape.
With a cry of recognition the simian started to descend the stairs, but at a noise from above he hesitated and then sprang back and out of sight.