“Our repeated search has given more and more substantiation to the professor’s claim. His cabinet, his laboratory, his office and his bolted doors have added mute testimony to his assertion. Four of us were witnesses to Crofton’s disappearance. Two of us — myself and Warlock — have admitted that devisualization must be the answer to Crofton’s departure.
“You, Cranston, have simply reserved opinion. For the present, we may regard your view as neutral. As for you, Darring, you hold to the belief that the whole affair was a hoax. Yet you have not produced any evidence to support your claim.”
“None,” interposed Darring, testily, “except that of common sense. You can’t make a man vanish, unless there’s a trick to it. I’ve got to see something more tangible.”
“We are dealing with a scientific matter,” asserted Barth, reprovingly. “The professor’s theory of devisualization has merit. Many facts, scientific ones, have been discovered that are quite as incredible as this one.
“However, we can resume this portion of the discussion later. What concerns us as much as Crofton’s disappearance is the matter of Crofton himself. Cardona, let us hear your exact statement once again, in reference to Miles Crofton.”
“Well,” declared Cardona, gruffly, “I’m only following a tip, as I said before. We’ve been looking for the crew that worked with Rouser Tukin. Hadn’t been able to trace any until to-night.
“Down at headquarters I got a phone call from a stool pigeon. Fellow that’s been A-1 reliable, the little I’ve used him. Just had a couple of minutes to put me wise to something, he said. So I listened.
“His story was that Miles Crofton was in with Rouser. What’s more, he swore that Crofton was the fellow who killed one of the policemen. Didn’t say where he got the dope, this stoolie didn’t, but he promised more next time he got in touch with me. But he told me where Crofton was. Said the guy was working for an inventor named Melrose Lessep. What’s more, the stoolie said the commissioner was going to be up at Lessep’s to-night.”
“Your man was remarkably well informed,” observed Barth, dryly. “You yourself did not know where to reach me, at first.”
“That only proves the stoolie knew his stuff,” returned Cardona. “I called the Cobalt Club; they told me where you were. So I called you, commissioner. Getting no reply, I started up, leaving Markham to keep calling you.”
“We know the rest,” declared Barth. “Therefore, we are safe in saying that a killer, an unseen killer, is at large. We can not hold Professor Lessep culpable. There is no way in which he could have known of his assistant’s past.
“But we must begin at once!” Barth thumped his fist upon the desk. “We must spare no effort in tracing this dangerous man. That is why I gave a full statement to the newspapers. The Unseen Killer is at large. It is up to you. Cardona, to find him.”
“You can’t track a man you can’t see,” objected Joe. “It’s easy enough to get pictures of Crofton, but what good will they be? If this wild stuff is on the level — if the guy’s lost to sight — how are you going to grab him?”
“That must be determined,” replied Barth, sagely.
Cardona waited for a further statement. None was forthcoming. The commissioner had propounded an unanswerable riddle.
A THIN smile showed upon the lips of Lamont Cranston. It was unobserved by the others.
“Where are you going to start?” quizzed Cardona. Then, answering his own question: “The professor looks like the best bet to me. If it wasn’t for him, we’d have Crofton right now. The way I figure it, commissioner, the professor is responsible.”
“Professor Lessep has committed no crime,” objected Barth. “His experiment was scientifically conducted.”
“If one can regard a hoax as a scientific experiment,” put in Darring. “I should think that the law could deal with the perpetrator of a hoax.”
“The professor has proven his sincerity,” declared Warlock, hotly. “This attempt to damage his reputation is unfair. It is not his fault that Crofton took criminal advantage of his invention.”
“We are back to the same point,” decided Barth, in an irritable tone. “Unless we can come to a definite agreement on this matter, we will arrive nowhere. I am willing to bring pressure upon Professor Lessep, provided that it can be done in a reasonable manner.”
“No pressure is necessary,” insisted Warlock. “Professor Lessep was quite willing for people to witness his experiment. He even set it in advance of the date originally scheduled. He offered no objection to making his demonstration under rigid conditions.”
“I have it!” exclaimed Darring, suddenly. “We can settle this matter very easily. Why not have the professor repeat the experiment?”
Cranston’s smile remained immobile. The suggestion had come at last. Darring had struck upon the obvious solution, the logical way to learn whether or not the devisualization system would stand a thorough test.
“Excellent!” said the commissioner. “That, at least, would establish one point, namely: whether or not your cry of ‘hoax’ is a fair one, Darring. But it offers a danger, besides.”
“What is that?”
“The possibility of putting a second person into the realm of the invisible. One is bad enough.”
Joe Cardona nodded at the commissioner’s statement. The detective added an opinion of his own.
“I’m supposed to track one fellow that I can’t see,” he declared. “Why double the odds against me?”
“My suggestion,” remarked Darring, “could produce the opposite effect. If devisualization is a genuine process, it can be used to advantage.”
“How so?” inquired Barth.
“By choosing the proper person,” replied Darring. “Detective Cardona, for instance. Why not dispatch him into the invisible?”
“Jove!” exclaimed Barth. “You’ve struck it, Darring. The effect would be tremendous!”
“It wouldn’t help me trace Crofton,” objected Cardona, in an uneasy tone.
“But it would give you a marvelous advantage,” argued Barth, with enthusiasm. “Furthermore, it would settle all this controversy. Of course, Cardona, I shall not insist that you take on this task—”
“I’M game,” interrupted Joe, “but it sort of gives me the creeps. It don’t sound real. I’ll take a chance on it, though, if the professor will stand for the deal.”
“I think I can persuade him to do so,” put in Warlock, a bit troubled. “He might object; but I think that he would listen to my arguments. I have sponsored this invention, in a sense. Let me communicate with Professor Lessep in the morning.”
“Very well,” agreed Barth. “A request from you, Warlock, would be better than an order from me. For a beginning, at least. Arrange for an experiment tomorrow night, with Cardona as the subject. If you fail, I shall handle the matter.”
“This experiment business works both ways, don’t it?” queried Cardona. “I mean the professor can bring a man back to sight, just like he can put him away?”
“So he claims,” stated Barth. “That was precisely what he intended to do with Miles Crofton; but the fellow made an escape in the midst of the experiment.”
“Have no qualms,” assured Warlock. “The professor is thoroughly reliable. I feel sure that you will encounter no danger when you visit his laboratory tomorrow night.”
“Agreed,” added Darring, mildly sarcastic. “You won’t have much to worry about, Cardona.”
“Why not?” questioned the detective, seeing significance in Darring’s tone.
“Because,” predicted Darring, “the professor will have some excuse for postponing the experiment. The thing is a hoax, I tell you. He will not dare to repeat it except with some person of his own choosing.”