"No, boss. We been all over the place, and we dug every spot we could get to earth in the cellar. Most of it's three-inch concrete, without a sign of a break."

"Did you look in the furnace?"

"We looked there the first thing. She ain't there."

There were several closets in the laboratory, and Phillips opened all of them and inspected them. As he moved near the big plate, Lambert uttered a cry of warning. "Don't disturb that, don't touch anything near it!"

"All right, all right," said Phillips testily.

The skeptical sleuths had cla.s.sified Lambert as a "nut," and were practically sure he had done away with Madge Crawford because she would not marry him.

Still, they needed better evidence than their mere beliefs. There was no corpus delicti, for instance.

"Gentlemen," said Lambert at last, controlling his emotions with a great effort. "I will admit to you that I am in trepidation and a state of mental torture as to Miss Crawford's fate. You are delaying matters, keeping me from my work."

"He thinks about work when the girl he claims he loves has disappeared," said Doherty, in a loud whisper to Phillips. Doherty was one of the sleuths who had been digging in the cellar, and the hard work had made his temper short.

"You must help us find Miss Crawford before we can let you alone,"

said Phillips. "Can't you understand that you are under grave suspicion of having injured her, hidden her away? This is a serious matter, Professor Lambert. Your experiments can wait."

"This one cannot," shouted Lambert, shaking his fists. "You are fools!"

"Steady now," said Doherty.

"Perhaps you had better come with us to the district attorney's office," went on Phillips. "There you may come to your senses and realize the futility of trying to cover up your crime--if you have committed one. If you have not, why do you not tell us where Miss Crawford is?"

"Because I do not know myself," replied Lambert. "But you can't take me away from here. I beg of you, gentlemen, allow me a little more time. I must have it."

Phillips shook his head. "Not unless you tell us logically what has occurred," he said.

"Then I must, though I do not think you will comprehend or even believe me. Briefly, it is this: yesterday morning I was working on the final series of experiments with a new type of harmonic overtones plus a new type of sinusoidal current which I had arranged with a series of selenium cells. When I finally threw the switch--remember, I was many weeks preparing the apparatus, and had just put the final touches on early that morning--there was a sound such as never had been heard before by human ears, an indescribable sound, terrifying and mysterious. Also, there was a fierce, devouring verditer blue light, and this came from the plates and studs you see, but so great was its strength that it got out of control and leaped about the room like a live thing. For some moments, while it increased in intensity as I raised the power of the current by means of the switch I held in my hand, I watched and listened in fascination. My instruments had ceased to record, though they are the most delicate ever invented and can handle almost anything which man can even surmise."

The perspiration was pouring from Lambert's face, as he recounted his story. The detectives listened, comprehending but a little of the meaning of the scientist's words.

"What has this to do with Miss Crawford?" asked Doherty impatiently.

Phillips held up his hand to silence the other sleuth. "Let him finish," he ordered. "Go on, professor."

"The sensations which I was undergoing became unendurable," went on Lambert, in a low, hoa.r.s.e voice. "I was forced to cry out in pain and confusion.

"Miss Crawford evidently heard my call, for a few moments later, just as the terrific unknown force reached its apex, she dashed into the laboratory, and stepped across the plate you see there.

"I was powerless. Though I shut off the current by a superhuman effort, she--she was gone!"

Lambert put his face in his hands, a sob shook his broad shoulders.

"Gone?" repeated Phillips. "What do you mean, gone?"

"She disappeared, before my very eyes," said the professor shakily.

"Torn into nothingness by the fierce force of the current or sound.

Since then, I have been trying to reproduce the conditions of the experiment, for I wish to bring her back. If I cannot do so, then I want to join her, wherever she has gone. I love her, I know now that I cannot possibly live without her. Will you please leave me alone, now, so that I can continue?"

Doherty laughed derisively. "What a story," he jeered.

"Keep quiet, Doherty," ordered Phillips. "Now, Professor Lambert, your explanation of Miss Crawford's disappearance does not sound logical to us, but still we are willing to give you every chance to bring her back, if what you say is true. We cannot leave you entirely alone, because you might try to escape or you might carry out your threat of suicide. Therefore, I am going to sit over there in the corner, quietly, where I can watch you but will not interfere with your work.

We will give you until midnight to prove your story. Then you must go with us to the district attorney. Do you agree to that?"

Lambert nodded, eagerly. "I agree. Let me work in peace, and if I do not succeed then you may take me anywhere you wish. If you can," he added, in an undertone.

Doherty and the others, at Phillips' orders, filed from the laboratory. "One thing more, professor," said Phillips, when they were alone and the professor was preparing to work. "How do you explain the fact, if your story is true, that Miss Crawford was killed and made to disappear, while you yourself, close by, were uninjured?"

"Do you see these garments?" asked Lambert, indicating some black clothes which lay on a bench nearby. "They insulated me from the current and partially protected me from the sound. Though the force was very great, great enough to penetrate my insulation, it was handicapped in my case because of the garments."

"I see. Well, you may go on."

Phillips moved in the chair he had taken, from time to time. He could hear the noises of his men, still searching the premises for Madge Crawford, and Professor Lambert heard them, too.

"Will you tell your men to be quiet?" he cried at last.

There were dark circles under Lambert's eyes. He was working in a state of feverish anxiety. When the girl he loved had dematerialized from under his very eyes, panic had seized him; he had ripped away wires to break the current and lost the thread of his experiment, so that he could not reproduce it exactly without much labor.

The scientist put on the black robes, and Phillips wished he too had some protective armor, even though he did believe that Lambert had told them a parcel of lies. The deaf mute's story was not too rea.s.suring. Phillips warned his companions to be more quiet, and he himself sat quite still.

Lambert knew that the sleuths thought he was stark mad. He was aware of the fact that he had but a few hours in which to save the girl who had come at his cry to help him, who had loved him and whom he loved, only to be torn into some place unknown by the forces which were released in his experiment. And he knew he would rather die with her than live without her.

He labored feverishly, though he tried to keep his brain calm in order to win. His notes helped him up to a certain point, but when he had made the final touches he had not had time to bring the data up to the moment, being eager to test out his apparatus. It was while testing that the awful event had occurred and he had seen Madge Crawford disappear before his very eyes.

Her eyes, large and frightened, burned in his mind.

The deaf mute, Felix, a small, spare man of about fifty, sent the professor some food and coffee through one of the sleuths. Lambert swallowed the coffee, but waved away the rest, impatiently. Phillips, watching his suspect constantly, was served a light supper at the end of the afternoon.

There seemed to be a million wires to be touched, tested, and various strange apparatus. Several times, later on in the evening. Lambert threw the big switch with an air of expectancy, but little happened.

Then Lambert would go to work again, testing, testing--adjusting this and that till Phillips swore under his breath.

"Only an hour more, professor," said Phillips, who was bored to death and cramped from trying to obey the professor's orders to keep still.

A circle of cigarette-ends surrounded the sleuth.

"Only an hour," agreed Lambert. "Will you please be quiet, my man?

This is a matter of my fiancee's life or death."

Phillips was somewhat disgruntled, for he felt he had done Lambert quite a favor in allowing him to remain in the laboratory for so long, to prove his story.