Childs supplied the light.

"This is indeed a pleasure," said Childs, rubbing his hands. "I have heard of you often, Mr. Arnaud, through - er - through mutual acquaintances, you might say. I have often wished to meet you."

"Rather nice office you have here," commented the visitor, looking curiously about him.

"It's unpretentious, Mr. Arnaud," returned Childs, "and it's very small. You see, Mr. Barr and myself are frequently out of town. We scarcely need an office but the Financial Building is so widely known that it makes an excellent permanent address."

Arnaud nodded and continued to look about him. Childs waited expectantly. He was keyed up with enthusiasm.

This was a real opportunity. Barr Childs specialized in speculative investments, and a man of millions would make an ideal customer.

"I just came in to make your acquaintance," began Arnaud. "You see, I occasionally seek unusual fields for my investments. Your concern was recommended to me.

"I thought that I would like to meet either you or Mr. Barr, so that in the future you could keep me posted on anything that might be of interest."

"Gladly!" exclaimed Childs. "Gladly, Mr. Arnaud. You see, our concern is -"

The girl opened the door of the private office. Childs hesitated for a moment. Then he rose.

"I should like to have you meet Mr. Warfield," he said, turning to Arnaud. "He is an excellent promotion man with whom we have had some very successful dealings.

"Of course, you understand, Mr. Arnaud, that Mr. Warfield is - er - well, all his negotiations should be conducted through us. He has many plans, and whenever they are sound, we handle them."

"I see," replied Arnaud, nodding.

"Tell Mr. Warfield to come in," ordered Childs.

A thin man of medium height entered the office. His face was that of an adventurer - long, sallow, and marked by thin, deep lines. He bore a worried expression that seemed natural.

He had a short, black mustache and a prominent nose above it. His eyes were piercing, and they turned immediately toward the visitor.

The shrewdness of his glance was met by the shrewdness of Henry Arnaud's gaze. Childs made the introduction. Arnaud arose and shook hands.

Childs drew up a chair on the other side of the desk. Before Warfield could step toward it, Arnaud had crossed to the new chair and had quietly taken his seat there.

There was nothing surprising in his action. It simply left the original seat for Perry Warfield.

The sallow-faced man was starting toward the vacant chair when Childs proffered a cigar. Warfield lighted it while Childs went behind the desk.

Then, amid a momentary silence, Warfield stepped toward the empty chair, which was directly in front of the unused typewriter desk in the corner of the office.

Childs was busy at his desk for the instant. Warfield was puffing his cigar. Henry Arnaud was listening attentively although his expression did not indicate it. He was slightly forward in his chair; that was all.

As Perry Warfield sat down, there was a click from somewhere behind him. The sound was m.u.f.fled; otherwise its sharpness would have attracted immediate attention. As it was, only Henry Arnaud detected it.

His expression did not change, but a slight gleam of satisfaction shone in his eyes as he relaxed in his chair.

Then his gaze turned toward the window, and he puffed his cigar thoughtfully. His mind seemed to be puzzling over something.

Childs began a brisk conversation. It was intended for the benefit of both Henry Arnaud and Perry Warfield. It dealt chiefly with investments.

Arnaud listened with feigned interest. Warfield nodded, but kept chewing the end of his cigar. The man was nervous, although he tried not to show it. At last, during a lull in the conversation, he spoke to Childs.

"Any new developments?" he asked.

"Nothing spectacular," replied Childs. "One or two matters I can speak to you about, but they can waituntil later."

"Don't let me interrupt," began Henry Arnaud, starting to rise.

"Stay right where you are, sir," said Childs. "Why don't you come back later, Perry?" The last remark was to Warfield.

"Think I will," said the sallow-faced man. He became suddenly courteous as he arose and shook hands with Henry Arnaud. "I'll be moving along," he said to Childs. "There's just one point"

"I'll see you to the elevator," suggested Childs. "Stay right here, Mr. Arnaud. I'll only be a minute."

The two men went into the outer office and thence to the corridor. The door of the private office remained open behind them.

Henry Arnaud looked quickly into the outer office. The girl was facing the window. Moving with amazing stealth, Arnaud reached behind the bookcase and brought out the interior of the bomb. He moved to the typewriter desk.

There was no click as he probed the lock. The top of the desk moved noiselessly. The top of the bombsh.e.l.l was loose; it required but a few seconds for Arnaud to replace the charge beneath the detonator and to close the desk again.

Then he was back in his chair, puffing his cigar meditatively when Childs entered.

The two men talked investments for half an hour. Childs was in an excellent humor when his visitor left.

He felt sure that he would soon number Henry Arnaud among his clients.

The morning went by satisfactorily. Childs went out to lunch and returned. Several persons called to see him. Some were ushered into his private office while he was temporarily absent.

It was a busy day, which reached its climax when Childs received a long-distance call from his partner, at four o'clock. He had scarcely hung up the receiver when the girl entered, with a short, dark-faced man behind her. The visitor spoke before she had a chance to introduce him.

"Mr. Childs," he said, "I'm Detective Cardona, from headquarters. I want to make a search here - on a tip-off I received today."

"What - what's it all about?" stammered Childs.

"I'll tell you later," said Cardona briskly. "There's no time to lose, right now. I'd like to look in that closet.

No, wait a moment" - his eyes had noted the typewriter desk in the corner - "what's in there?"

"Nothing," replied Childs, in a puzzled tone. "It's an empty typewriter desk - that's all -"

Cardona was looking at the lock.

"Have you the key?" he asked.

Childs supplied it.

Cardona opened the desk cautiously. An exclamation came from his lips. He bent over the desk and made a quick inspection. Then he turned to Childs and shook his head.

"This is your lucky day!" he said. "By rights you should be dead - blown out through the side of thebuilding with this whole office!"

He lifted the box from within the desk and exhibited the bomb which it contained.

"The detonator has struck," he said. "But it has failed to explode the charge! When it occurred, I do not know. Probably yesterday afternoon. This would have been the fifth explosion - but somehow it went wrong!"

With these words, the detective left the office. When two plainclothesmen entered from the corridor to complete their superior's investigation, they found Childs collapsed behind his desk, his hands gripping the arms of his chair, his eyes staring in horror!

CHAPTER VI. DOCTOR ZERNDORFF ACTS.

"SO!" exclaimed Doctor Zerndorff.

He was standing in his laboratory, a white-walled room that adjoined the living quarters of his apartment.

Before him lay the separated portions of the bomb which had been brought from the office of Barr Childs. Beside him stood three men - Inspector Burke, Detective Cardona, and a secret-service investigator.

"You have found something?" questioned the inspector.

"Something?" returned Zerndorff. "Something, yes? It is everything that I wished! Now all is plain!"

He turned to his three companions and leaned one elbow upon the shelf beside him.

"It is but one man who could have made this bomb," he declared. "I could not have made myself believe that he was here, in this America. But now, I can tell it all!"

"Who is he?" questioned Cardona eagerly.

"His name is Isidor Vervick," replied Zerndorff.

"Where is he?"

"He is dead now!"

Cardona started in amazement. He could not understand the sudden knowledge displayed by Zerndorff.

The criminologist smiled and went on.

"You must know and understand these men," he said. "They do not change their actions, because they are men who hide. This man Vervick - I see him plain.

"He was a bright man, this way" - he tapped I forehead with his fingers - "and he was also a fool, this way." He tapped his forehead a second time.

There was a momentary silence, while Zerndorff picked up bits of mechanism and examined them again.

"I can tell you this," he said. "If Vervick had written, in letters, his own name upon these pieces metal, it would not have been more plain to me.

"I can tell you also this. By these pieces of metal, I see that the bomb was made in America, here. But I had thought that Vervick was not here!" "But how do you know that he is dead?"

"Because he was the fool! It is for others that he has always done work. These bombs have been made by him, as others have told him to do.

"He was a man who hid. He did not put the bombs where they would explode. He was a fool, that wished for money - and would believe all that was told to him!

"Do you bring to your mind that explosion in the office of the newspaper - the Cla.s.sic, it was called?"

Cardona nodded.

"Who was the man killed there? The man they did not know? I can tell you that man and his name! It was Isidor Vervick!

"He had made the bombs. He had given them to those who paid for them. He saw five thousand dollars.

He went to warn - and before he could warn, he was killed!"

"But who planted the bombs?" questioned Cardona.

"You have not yet found that out? Well, now I shall tell you where to look!

"In New York there must be two men - one is Italian, Michael Sforza. The other - he is Russian, Grigori Pecherkin. Only for them would Vervick have done this work.

"They have been here in New York. What names they have now to call themselves by, I do not know.

But they have done nothing here except to talk of communism. But now, I can tell you plain, they have to work with Vervick!"

Before Cardona could speak, the secret-service man grunted his accord with Zerndorff's remarks. This man was no stranger to either Burke or Cardona. He was Hal Steelman, who had cooperated with the New York police on previous occasions.

"I can trace both of those men," he said. "Sforza is working in a Brooklyn restaurant, under his own name. Pecherkin calls himself Peterson. He hangs around on the East Side.

"We've had nothing on either of them, until now. But we ought to get some good evidence before we grab them!"

An attendant entered the laboratory and spoke to Doctor Zerndorff in German. The criminologist turned to Inspector Burke.

"There is a call for you from headquarters," he said. "You wish the telephone, yes? It is waiting with the call."

Burke left, with Cardona at his heels. He returned a few minutes later, alone. His face bore a smile of grim satisfaction.

"They've rounded up some suspects," he said. "Cardona's gone on duty. We'll hear from him at headquarters."

He jotted down the information which Doctor Zerndorff had given him. He compared notes with Steelman. Then he departed for headquarters and the secret-service man went with him.

It was late in the evening when they left. It was not until the next morning that Doctor Zerndorff heardfrom them. Then he had a visitor in the person of Detective Joe Cardona. The Italian-American grinned when Zerndorff entered the room where he was waiting.

"Well?" asked Doctor Zerndorff.

"Have you seen the newspapers?" questioned Cardona.

"Not as yet," replied Doctor Zerndorff methodically. "I have just breakfasted and I do not read until after then - never."