CHAPTER XXX.
THE MYSTERY SOLVED.
When the opening at the head of the stairs had closed upon Billieand he realized that he was shut in a subterranean passage, for aminute his heart sank within him.
He had tried to find an opening at the top of the opposite stairsand had failed, and he did not know that he would have any bettersuccess in trying to find a way to open the place through whichhe had descended.
"Nobody on earth knows that I am down here," he thought, "andwith Santiago sick and maybe dying, no one on earth probablyknows that there is such a passage."
But Billie was not the lad to sit down and cry. He had been intight places before and he had an abiding faith in his ownability to do things. Therefore, he called up his courage andslowly mounted the stairs leading to Santiago's patio.
At the top of the stairs he found himself confronted by exactlythe same condition as he had found on the opposite side.
"But there is this difference," muttered Billie. "I know thatthere must be some sort of a crack where that slab fell back."
He held the electric bull's-eye close to the stone andscrutinized every spot.
Not a single crack could he spy.
Then he took out his big jack-knife and prodded with it clearacross the width of the stairway.
There was nothing but solid stone.
"Looks kind o' desperate," he told himself, "but I have simplygot to find an opening."
Again he prodded the place over without result.
"It's no use," he finally said to himself. "If I am to get out ofhere, help will have to come from somewhere outside. But how canit?"
He sat down on the stairs and thought deeply.
"If it is as I think," he mused, "these stairs have been usedrecently. The very fact that Ambrosio is prowling around here isproof that Strong must have been here at some time. But where isStrong?"
He slid down several steps and threw the light of his torchacross to the opposite stairs.
"Bang!" went something that sounded like a falling stone.
Billie sprang to his feet.
"Click! Bang!" and down the opposite stairway streamed a ray oflight.
Billie shut off his electric torch and waited.
Then on the steps there appeared a foot, then another, until awhole human body was in sight. Then "click, snap!" and the lightdisappeared.
"By George!" exclaimed Billie under his breath, "there's a man onthe stairs right opposite to me. Who on earth can it be?"
His first inclination was to turn on the light, but on secondthought he decided not to.
"I'll let him set the copy," thought Billie. "It's a mighty goodthing to be able to spring the surprise."
He drew his automatic and stood ready for any emergency.
It was still as a tomb.
He could hear his own heart beat and he could also hear the heavybreathing of the other man.
"Sounds like he had been running and was just catching hisbreath," was Billie's mental comment.
After some minutes the man's breathing became more quiet andBillie heard him slowly descending the stairs.
"This won't do," thought Billie. "He probably has some kind of alight, and if he gets on the landing and I'm up here, I'll belike a man up a tree."
The lad sat down and slowly slid toward the bottom.
Being only a few steps from the landing, Billie was down first.He crowded to the right and listened.
The other was now nearly on the landing. Now he was on thelanding, hugging the wall on the side opposite Billie. Now theypassed each other, or rather the man passed Billie, for Billiestood perfectly still.
It seemed as though he must hear Billie's breathing, but if heheard anything he must have thought it his own echo, neverdreaming that he was not alone in the passage.
Now Billie could hear him ascending the stairs leading toSantiago's house, and his hope rose high.
"He must know how to open the floor," thought Billie. "I'll beright there when he does."
Silently as a cat Billie crept up the stairs behind his unknowncompanion.
Near the top the man stopped and a minute later he flashed anelectric light against the stone overhead. Another minute and heheaved with the top of his head and the slab slid back.
"And now," exclaimed Billie in a deep voice, "put your hands overyour head!"
Whether from fear or from the unparalleled surprise caused byhearing a human voice at such a time and in such a place, insteadof obeying Billie's command, Strong's hands--for Strong itwas--fell limp at his side and his electric torch fell to thestones beneath his feet.
"All right," continued Billy, "if that's the way you feel aboutit; but just remember that a single false move and I'll cut thisautomatic loose among your ribs. Now climb out a step at a time."
With face as white as marble at the shock he had just sustained,Strong obeyed implicitly and Billie was soon standing on thestone patio, looking Strong in the face.
"You're a good one, you are," he said sarcastically. "I shouldthink you'd be ashamed to call yourself an American."
"What do you mean?" asked Strong in a trembling voice.
"Why, first of all, stealing from the bank, and then selling yourown countrymen to the Mexicans."
"Who have I sold?"
"Do you mean to say that you didn't sell Gen. Funston to thegreasers for ten thousand dollars?"
"Of course I do!" in a somewhat stronger voice.
"Perhaps you'll deny that you are Strong, the mountebank. Youdon't think for one minute that I don't know you in spite of yourmake-up, do you?"
"No, I'll admit that I'm the mountebank. As for my name that isof small importance in a country like this. But I did not sellGen. Funston, as you put it. I knew the man I pointed out was notFunston and I knew that as soon as the Mexicans found it out theywould let him go. Some one might have told them rightly. As itwas I spoiled their game and I got the money. Do you think it anycrime to do that?"
"That's a matter I am not in a position to discuss," was Billie'sanswer. "But how about robbing the bank?"
"I had as much right to the box as any one."
"You'll have to prove that to some one besides me; all I can dois to turn you over to the authorities."
"Never!" cried Strong. "I'll die before I'll rot in a Mexicanjail!"
He uttered a peculiar noise and before Billie could imagine whatit meant, he felt himself seized from behind by a pair of hairyhands.
He had been in that clutch once before and recognized in aninstant that he was in the grip of the ape.
He gave one loud cry for help and then turned loose with hisautomatic.
The tumult which followed is beyond description. Billie's shoutwas as nothing compared to the cry of the ape as one of thebullets struck him in the leg and another pierced his foot.Loosing his hold upon the lad, he grabbed for the weapon, butBillie managed to evade him and would undoubtedly have slain theanimal had not Strong sprung to his assistance, with the resultthat in another minute Billie was disarmed.
Ill would the lad have fared then, at the hands of his twoassailants, had not the noise attracted to the scene severalsoldiers, while an instant later came a loud shout as Donald andAdrian dashed into the patio.
On the other side of the square they had heard Billie's shout,followed by the automatic, and had rushed to his aid.
In another minute both Strong and his hairy friend were overcomeand securely bound.
"Where did you find him?" asked Donald, pointing to Strong.
"Down there," was Billie's reply, as he pointed toward the stillopen underground passage way.
"How did he get there?"
"I suppose he entered from a similar entrance in Don Esteban'spatio. I have had an idea all the time that there was some reasonfor the position of these two houses."
"But it doesn't lead into the bank. How could he steal the boxout of the vault?"
"There is the real thief!" exclaimed Billie, pointing to the ape."He sneaked in wh
ile Strong kept the bank employes engaged. Bysome mistake in his understanding he put the envelope back in thebank the next day instead of putting back the box. It was he whocrawled through the bars into Santiago's library. He was also thedevil who scared the maid almost into fits."
"Well! Well!" exclaimed a voice from the gateway. "I never couldhave believed it."
The voice was that of Don Esteban, who had entered while Billiewas speaking.
"I have come to see this strange man, Santiago Ojeda," heexplained. "What says the doctor?"
"Here comes the doctor now," announced Adrian as the physicianmade his appearance in the gateway. "He can speak for himself."