Felipe Jalisco always leaped to his feet like a cat when a knock sounded on his door. He could tell in a twinkling if it was Hagan who knocked. This time he knew it was not. The rap had been faltering and feeble.

Jalisco's hand sought the knife he always carried.

"Who is it?" he demanded.

The reply to this question was a repetition of the hesitating knocking.

"Who are you? and what do you want?" sharply cried the Mexican lad.

"I am very sorry to disturb you," said a cracked, unsteady voice. "I have the next room. You can do me a favor."

Now Felipe was lonesome. Staying hidden in that squalid room had made him wretched and homesick. He longed to talk to some one, and he cautiously opened the door.

Outside stood a man bent as if with age, leaning heavily on a crooked cane. He was the picture of poverty. His threadbare clothes had been mended in many places. His dirty, gray hair was long and uncombed. The soles of his shoes were almost wholly worn away, and the uppers were broken in two or three places. He brushed his hair back from his eyes with a trembling hand that seemed unfamiliar with soap and water.

"I hope I have not disturbed you," he said meekly. "I have torn the sleeve of my coat on a nail. I would like to borrow a needle and thread to mend it. I must keep myself looking as well as I possibly can, for my lawyer may call any moment to inform me that I have won my suit and am a very wealthy man."

"I am sorry, seÑor," said Felipe; "but it is not my fortune to possess a needle and thread."

The old man lifted one trembling, curved hand to the back of his ear, which he turned toward the speaker.

"I didn't quite get your answer," he said. "I am a trifle deaf—only a trifle."

Felipe raised his voice.

"I have not a needle and thread. I would willingly assist you if I had. I am sorry."

"I am sorry, too," sighed the old man, looking regretfully at the rent in his sleeve. "I should be greatly mortified if my lawyer came and found me in this condition."

The boy felt that this wretched old man would be better company than none at all.

"Won't you come in and sit down?" he asked.

"Eh?"

"I would be pleased to have you come in, seÑor."

"Oh, I don't know. I'm not dressed for calling. But then, as we room near each other, I presume you'll see me often in my working clothes."

He entered the room and lowered himself upon the chair that Felipe placed. The boy sat on the bed.

"Did I understand you to say, seÑor, that you have the next room?"

"Eh? A little louder, please."

Jalisco repeated the question.

"Yes, yes," answered the old man. "I have just taken it. Had to pay a week in advance, and it happens that it took all my money, therefore I'm unable to purchase a needle and thread. But," he quickly added, "in a very few days, when the law gives me my rights, I shall have money enough to purchase all the needles and all the thread in this city without realizing that I have spent anything at all."

"Then you expect to come into an inheritance, seÑor?" questioned the boy loudly.

"Not just that," was the answer. "I shall obtain my rights. I shall be given a just reward for the invention that was stolen from me and has made other men rich."

Between the old man and the boy there seemed to be a bond of sympathy which the latter felt.

"So you, too, have been robbed?" he cried.

"Basely robbed!" declared the visitor nodding his trembling head. "My name is Roscoe Spooner. I invented what is known as the Guilford Air Brake. The product of my brain was stolen from me by Henry Guilford, who has made so much money from it that he is now a very rich man. But everything he possesses, his splendid home, his carriages, horses, and his yacht, are rightfully mine. He has enjoyed his stolen wealth a long time, but it will not be his much longer. My suit against him must be decided in my favor, and then I shall come into my own."

Felipe was interested.

"How long ago did you perfect this invention?"

"How long? It seems almost a hundred years; but it really was not fifteen."

"How was it stolen by this Guilford, seÑor?"

"I trusted him. He told me he would furnish the capital and would place my invention on the market. I believed him an honest man. I permitted him to have my model. He patented it, calling it the Guilford Air Brake. When I demanded my just share of the profits, he laughed in my face and called me a crazy old fool. He even had me arrested for annoying him. And my invention has filled his pockets with hundreds of thousands of dollars."

"That was in truth a most dishonest thing, old gentleman. What then did you do?"

"I found a lawyer to take the case and brought suit against him."

"I would have killed him!"

"I have thought of that. Once I did borrow a pistol and go in search of him; but when we met I could not bear to think of the terrible thing I had contemplated, and he never knew how near to death he was."

"It is not my way. At least, had you tried, you might have frightened him into giving you something."

"Had I tried that, it would have cost me my liberty. I am sure he would have lodged me in prison."

"Perhaps so," muttered Felipe. "You're a simple old fool, and you wouldn't know how to work it."

"What did you say?" asked the old man, who had seen the boy's lips move, but apparently had not understood his words.

"This Guilford must be a very wicked man. Your suit against him was useless?"

"The verdict favored him, but I appealed. In the end I shall win. My lawyer has told me so. He may appear to-day, or to-morrow, or the next day, and inform me that I have won. I am looking for him any time."

"And he'll never come," muttered the boy.

"I shall not stay here long," asserted the old inventor. "My room is very poor, but when I think that it is only for a short time that I must occupy it, then I am contented. I had a room in another place, where it cost a great deal more: but I decided to move and economize while waiting for my rights."

Felipe wondered how the old man existed, deciding at once that he must pick up a meagre living by begging.

"I, too, am waiting here until I come into my rights," said the boy. "Like you, I have been robbed. Unlike you, I'll not wait so long. Either I'll have what is mine, or I'll kill the man who has robbed me."

"'Thou shalt not kill.' To have the stain of blood on one's hands must be terrible."

"The Jaliscos belong to a family that kills."

At this juncture there came another knock at the door, but this time Felipe knew who it was.

He had the door open in a moment, and Bantry Hagan walked in.

"Oh, it's company you have, me boy!" exclaimed the Irishman, looking wonderingly at old Spooner.

"A gentleman who has the next room. He dropped in to borrow a needle and thread."

"It's careful you'd better be, Felipe."

"Never fear; it is all right."

The old man dragged himself up from the chair.

"I'll go back to my room," he said. "I hope I have not taken up too much of your time."

"Not at all, seÑor. I shall be pleased to have you come again."

When old Spooner was gone and the door closed, Hagan observed:

"What cemetery did you dig him from, Felipe? Who is he, me boy?"

"A deranged old man, who thinks he has invented something and that it was stolen from him. He expects to recover his rights and become very rich. He has the next room."

"Then it's careful we'd better talk, for he may hear."

"No danger, SeÑor Hagan, for he is extremely deaf. I am glad you came, for I was tired shouting to make him understand me. What is the good news you bring?"

"Things are moving, Felipe. By my soul, I believe this vengeful being is really keeping his oath to make it warm for Frank Merriwell. When I was here last night I told you that old Gripper Scott had been taken ill and that Warren Hatch was in the hospital from a smash-up that had broken several of his ribs."

"Si, seÑor."

"Felipe, my eyes have been opened since last night. Alvarez Lazaro dined with Watson Scott the night the latter was taken ill. He talked confidentially with the chauffeur of Warren Hatch a short time before Hatch was smashed up in his automobile."

"You think, SeÑor Hagan, you think—what?"

"Whist! Don't be after breathing that I told you; but it's a fancy I have that SeÑor Lazaro could tell us the cause of the mysterious illness of Watson Scott, and could explain just why the automobile of Warren Hatch plunged down an embankment and smashed him up, while his chauffeur leaped and escaped. Lazaro is striking first at the railroad builders."

"And I am cooped here!" cried the boy. "I'll stay no longer! Why should I? I'm going out! I'm going to have a part in this!"

"And it's pinched you'll be in a minute."

"The police——"

"Are looking for ye now, just the same. Besides that, this Merriwell is doing his best to get track of ye. I didn't wish to worry you, so I didn't tell how he tried to follow me last night when I came here."

"Did he? Did he?"

"Sure he did. I don't know just where he ran across me, but first I knew he was tracking me through the streets."

"You came just the same."

"When I had neatly given him the slip. Oh, I fooled him, Felipe. I left him to wonder where I had gone."

"Lazaro followed you here."

"Because I did not get my eye on Lazaro, as I did on Frank Merriwell. Don't worry, boy; he'll never find ye through me."

"If he came here, he'd not get away alive!" hissed Felipe.

"Make no mistake about him, me lad; he can fight with the best of them. Some friends of his have arrived in town, and I think they're taking up the most of his attention now. It's planning some sort of a trip they are."

"I can't stay here in this place much longer, SeÑor Hagan. I shall go mad!"

"Wait a little. I met Lazaro this morning on Broadway. Says he, 'If you see Felipe to-day, tell him I will come and cheer his heart with good news this night.' I'll drop round myself, so it's not lonesome you'll be."

"Well, I will wait a little longer," said Felipe.

Had it been possible for Hagan and Felipe to look into the next room just then they would have been greatly surprised by the singular conduct of old Spooner.

Between the two rooms there was a door, one panel of which was cracked. No longer bent and shaking, the man in the adjoining room was standing with one ear pressed close to the split panel. In spite of the fact that he had seemed quite deaf while talking with the Mexican lad, his appearance just now was that of one listening intently.

Shortly after Hagan left, Felipe heard the door of old Spooner's room open and close, following which there was a faltering, shuffling step on the stairs and the thump, thump, thump of a cane, growing fainter until it could be heard no longer.

"The old man has gone out to beg," thought Jalisco.

After leaving the house, old Spooner faltered along the street, turned several corners, and finally arrived at another house, which he entered.

Ascending one flight of stairs, he unlocked a door and disappeared into a hall room, closing and locking the door behind him.

Fully thirty minutes passed before that door was unlocked and opened again.

Out of that room stepped a tall, straight, clear-eyed, manly looking youth, who bore not the remotest resemblance to the tottering old man who had entered.

This youth ran down the stairs, left the house, and turned westward, swinging away with long strides.

"Merriwell," he muttered, as he walked, "I almost believe you could have been a successful detective had you chosen that profession."

Some time later he arrived at a Broadway hotel and found assembled in a suite of rooms several persons, who greeted his appearance with exclamations of great satisfaction.

"We were getting worried about you, Frank," declared Inza, hurrying to meet him and giving him both her hands. "We had almost decided that something serious had happened to you."

"Didn't know but this new freak with the snowy hair had gobbled you up," said Bart Hodge.

"Told you he was all right," grunted Bruce Browning, who was lounging on the most comfortable chair in the place.

"You were so weary you didn't want to bother about going to make inquiries for him," said Elsie Bellwood. "Mrs. Medford was on the point of applying to the police."

"According to all the stories I hear," put in Mrs. Medford, "I believe it best for you to get out of this wicked city just as soon as possible, Frank."

Frank laughed.

"If everything goes well," he declared, "we'll be ready to start by day after to-morrow."

"Tell us just where you have been and what you have been doing," urged Inza.

"I've been doing a little character work."

"Character work?"

"Yes. I can't get over my old penchant for acting."

But, although they were very curious, he evaded making a complete explanation then.

A little later he found an opportunity to speak with Bart and Bruce without being overheard by the girls or Mrs. Medford.

"Look here, you two," he said, "I'm going to need you to-night. Don't make any plans about dinner or the theatre. Provide yourselves with pistols, for you may have to use them. Be ready when I want you."

"This is rather interesting," said Hodge. "What's the game, Frank?"

"The game will be to capture a nice little bunch of human tigers."

"Human tigers!" grunted Browning. "That sounds like the real thing, old man. Can't you put us wise a little more?"

"Not now. I'm going to call up my friend Bronson, the detective, and get him into it, for I believe he will be needed. I hope that this night I'll be able to effectually checkmate some very dangerous rascals."

Merry did not use the phone in the suite, but went down to the booths in the hotel lobby. There he called up police headquarters and asked for Bronson.

"He's just come in," was the answer. "Have him to the phone in a moment."

Directly Bronson himself inquired what was wanted.

"This is Merriwell," explained Frank. "Is there anything that will prevent you from giving me your services to-night?"

"Well, nothing that I know of, if the business is important; but I'll have to know what's doing in order to make it right here."

"I don't like to explain over the phone," said Frank. "If you can wait, I'll jump into a cab and come right down to tell you all about it."

"I'll wait," was the assurance.

Merry lost no time in taking a cab for police headquarters, where he found the plain-clothes man waiting for him.

"Bronson," said Merriwell, "I've found Felipe Jalisco."

"Have you? Well, it will give me some satisfaction to again get my hands on that slippery chap."

"But I believe I have found something far more important. You know I told you that I was convinced of foul play in the Watson Scott affair, and also in the seeming accident that happened to Warren Hatch."

"Which seems entirely improbable to me."

"I think I'll be able to convince you to-night that I was not mistaken in either case. Further than that, I hope to place within your grasp the wretch who drugged Scott and bribed Hatch's chauffeur to bring about that accident."

"If you can do that, and if we succeed in securing the villain, it will be a corking piece of work. I think it will prove the sensation of the hour."

"Listen," said Frank, "and I will tell you my plan."