“Walls — floors — ceiling — those could have been the only other modes of exit. They were solid. We are back again to the doors and the windows. All bolted. Any ordinary murderer would have been forced to leave door or window open.
“You can’t close a bolt through solid woodwork. You can’t push an arm through a window pane without breaking it. My verdict is the Unseen Killer. But this time he sent no warning.”
The commissioner paused. He stared through his spectacles, looking first at Cardona, who nodded; then at Cranston, whose expression remained unchanged. During the momentary lull, Amboy whispered to Norgan, who nodded nervously.
Commissioner Bart had caught the whisper. He stared inquiringly. Norgan coughed and mopped his forehead. Then, in a rather strained tone, he spoke.
“NATHANIEL HILDON did receive a warning,” he declared. “We intended to speak of it, Mr. Amboy and I, but we thought it best to wait until you had completed your inspection. You see, we—”
“A warning?” snapped Barth, querulously. “A warning — to Hildon? What kind of a warning?”
“A typewritten message—”
“From whom?”
“The Unseen Killer.”
Barth stood dumfounded. Then his eyes sparkled. Triumphantly, the commissioner looked toward Lamont Cranston. Then he asked, sharply:
“What became of that message?”
“I didn’t see anything of it,” put in Cardona. “I searched the room. If Hildon had it, the murderer could have lifted it.”
“That is what he must have done,” declared Norgan.
“How do you know?” demanded Barth. “Did you see the message, Norgan?”
“Yes,” nodded the square-jawed man. “I saw it at noon to-day, when we had lunch with Hildon. So did Amboy.”
A nod from Amboy corroborated this statement.
“Explain in full,” ordered Barth.
“To begin with,” stated Norgan, still a bit nervous, “I must mention that Hildon was — to an extent — associated with Amboy and myself in certain business enterprises. The three of us are erroneously reported to have made a fortune at the expense of the Centralized Power Corporation.”
“I have heard of that report,” returned Barth. “You do not need to go into details regarding your enterprise. Proceed with the matter of the note.”
“To-day,” resumed Norgan, “each of us received a threatening message. All the notes were exactly alike. We met at luncheon and discussed them.”
“You have such a message?”
“Yes. From the Unseen Killer.”
“Where is it?”
“Here.” Norgan produced a folded sheet of paper. Amboy did likewise. They passed the missives to Barth. The commissioner handed one to Cardona; then opened his and read aloud, while Cardona, nodding, acknowledged the identical wording.
Each message read as follows:
“A WARNING:
“You possess certain funds which represent ill-gotten gains. You are not alone. Two others share your spoils. They, too, are receiving warnings.
“All this wealth — not one cent excepted — must be delivered into my hands, intact. To pass me your hidden funds, you must first communicate with me.
“Issue a statement to the evening newspapers announcing that you have received a threat from me. Unless some such account appears by the final editions, one of you will be dead by tomorrow morning.
“THE UNSEEN KILLER.”
“Well?” questioned Barth, sharply. “Why did you not inform the police of these threats? You have witnessed the result. Hildon is dead—”
“We thought the notes a trick,” put in Amboy. “Some game, worked by enemies who have been trying to force us into admission of profits that we have not made.”
“Or a blackmailer’s scheme,” added Norgan. “Possibly the work of a crank — any one who might have read the newspaper accounts of the unseen murderer who slew Professor Lessep.”
“So you decided to do nothing about it?” quizzed the commissioner.
“Exactly,” admitted Norgan. “The three of us met, compared the messages that we had received and agreed to make this crank show his hand. We wanted no notoriety. We felt that we were safe.
“I went to my home on Long Island; Amboy to his apartment. Hildon came here. Then, about eight o’clock in the evening, I began to worry. About Hildon. I felt that his position would be the least secure. This district is secluded.”
“That is why you telephoned him?”
“Yes. At eight o’clock. No answer. I telephoned again. Still no response. I decided that servants must certainly be here, even if Hildon had gone out. So I drove in town and picked up Amboy. You know the rest, commissioner.”
BARTH paced for a few moments. Then he paused to eye the two threatened men. Amboy and Norgan looked solemn. Barth adjusted his pince-nez.
“I predict,” he said, wisely, “that you will receive new messages tomorrow morning. This Unseen Killer — Miles Crofton — possesses powers that are almost unlimited. We must draw him out.
“Notify me if you receive new threats. Then we will give him the statement that he wants. In the meantime, I shall place officers on guard at your respective homes.
“It seems obvious, after reading those threats, that the Unseen Killer did not want you to learn of Hildon’s death until the morning. That is why he muffled the telephone bell. His entire purpose is now explained.
“Despite the fact that you gentlemen have sought to shun publicity” — Barth paused dryly — “your names have appeared in print. Only yesterday, the newspapers carried an account of your proposed lawsuit against the Centralized Power Corporation.
“It is generally acknowledged that you gained profits through your transactions, even though the amounts may be exaggerated. By merely reading the newspapers, the Unseen Killer could have picked upon you two — with Hildon — as a trio of wealthy men.”
Amboy and Norgan stood silent. Having summed the case as he saw it, Wainwright Barth made prompt arrangements. He detailed officers to accompany both men to their homes. He saw Amboy and Norgan leave. Then, accompanied by Lamont Cranston, Barth went upstairs for a final examination of the room wherein Nathaniel Hildon had died. After that, Barth departed with Cranston.
A CLOCK chimed four. It was the same clock that Norgan and Amboy had heard, hours before.
Solemn strokes above the gloom that pervaded that isolated thoroughfare called Culberly Court.
Patrolmen heard it as they paced in front of the silent, almost ghostly houses that stood as relics of the past. The sound drifted to the alleyway at the rear of the old-fashioned homes. There, another patrolling officer caught the notes.
Blackness persisted from the shrouding trees of a parklike square across the way. Then came motion; inkiness detached itself from the gloom. A blot moved along the sidewalk, just within the area of a street lamp’s light.
A hazy form glided across the thoroughfare. It moved past the house where the green glass glowed above the front door. The strange shape entered the obscurity of the side areaway between Hildon’s home and the empty house that adjoined it.
Projecting ornamental bricks offered a hold for hands and feet. Eerily, a phantom figure scaled the wall close by a little alcove. Then the moving shape stilled. Batlike, it clung to the vertical surface.
A policeman was coming through the areaway. His flashlight flickered. Its beam reached the wall; but not quite high enough to reveal that form. The light went on. The Shadow, motionless as night itself, remained undiscovered.