Deep silence, then a long shuddering wail of terror, a stifled, strangling cry for help, the sound of a body falling, and again deep silence. A pause, and after awhile the tramp, tramp of heavy shoes through a lower hall. A door slammed and a man staggered out into a deserted street, haggard, trembling and with lips hard set. He reeled down the street and turned the first corner, waving his trembling hands fantastically.

Another pause, and spears of light flashed through the black night from the second floor of a great six-story tenement in South Boston, then came the sound of stockinged feet hurrying along the hall. Half a dozen horror-stricken men and women gathered at the door of the room whence had come the cry, helplessly gazing into one another’s eyes, waiting, waiting, listening.

Finally, from inside the room, they heard a faint whispering sound as of wind rustling through dead leaves, or the silken swish of skirts, or the gasp of a dying man. They listened with strained attention until the noise stopped.

At last one of the men rapped on the door lightly. There was no answer, no sound. Again he rapped, this time louder; then he beat his fists on the door and called out. Still a silence that was terrifying. Mute inquiry lay in the eyes of all.

“Break in the door,” said some one at length, in an awed whisper.

“Send for the police,” said another.

The police came. They smashed in the door, old and rotting from age, and two of them entered the dark room. One of them used his lantern and those who crowded the door heard an exclamation.

“He’s dead!”

Peering curiously around the corner of the door the white-faced watchers in the hall saw a man, dressed for bed, lying still on the floor. Two chairs had been overturned; the bed clothing was disarranged. One of the policemen was bending over the body, making a hurried examination. He finally arose.

“Strangled to death with a rope — but no rope here,” he explained to the other. “This is a case for a medical examiner and detectives.”

“What’s his name?” asked one of the policemen of a man who stood looking in curiously.

“Fred Boyd,” was the reply.

“Have a roommate?”

“No.”

The other policeman was fumbling about the table with his light. At last he turned and held up something in his hand.

“Look here,” he said.

It was a new wedding ring. The bright gold glittered in the lantern light.

An hour later a man turned from a side street into the avenue where stood the big tenement house, and swung along in that direction. It was the man who had left the lower door soon after the cries were heard on the second floor. Then his face had been haggard, distorted; now it was calm. One might even trace a line of melancholy and regret there.

Around the street door of the tenement was gathered a crowd of half a hundred curious ones, half-clad and shivering in the chill of the night, all craning their necks to see into the hall over the broad shoulders of a policeman who barred the door.

From a score of windows the heads of other curious ones were thrust out; there was the hum of subdued conversation.

The stranger paused on the outskirts of the little knot and peered curiously into the hall, as others were doing. He saw nothing, and turned to a bystander.

“What is it?” he asked.

“Man murdered inside,” was the short response.

“Murdered?” exclaimed the stranger, “who was it?”

“Fellow named Fred Boyd.”

A flash of horror passed over the stranger’s face and he made an involuntary motion with his hand toward his heart. Then he steadied himself with an effort.

“How was he — he murdered?” he asked.

“Choked to death,” said the other. “Somebody heard him yell for help a little while ago, and when a policeman came he smashed in the door and found him dead. The body was still warm.”

The stranger’s face was white as death now and his lips moved nervously. His hands, thrust deep into his pockets, were clenched until the nails cut the flesh.

“What time did it happen?” he said.

“The cop says about fifteen minutes to eleven,” was the reply. “One of the tenants who lived on the second floor, where Boyd had a room, looked at his clock when he got up after he heard Boyd shout, so they know just when it was.”

Uncontrollable terror glittered in the stranger’s eyes, but none noted it. All were intently looking into the hall waiting for something.

“Medical Examiner Barry and Detective Mallory are up there now,” volunteered the bystander. “The body will be coming out in a minute.”

Then an awed whisper went around: “It’s coming.”

The stranger stood peering on as the others did.

“Do they know who did it?” he asked. His voice was tense, and he fiercely repressed a quaver in it.

“No,” said his informant. “I heard, though, that a fellow had been up in Boyd’s room tonight, and the man who had the next room heard them talking very loud. They had been playing cards.”

“Did the man go out?” asked the stranger.

“Nobody saw him if he did,” was the reply. “I guess, though, the police know who he was, and they’re probably looking for him by this time. If they don’t know, Mallory’ll find him out all right.”

“Great God!” exclaimed the stranger between his tightly compressed lips.

The other man turned and looked at him curiously.

“What’s the matter?” he asked.

“Nothing, nothing,” said the stranger, hurriedly. “Look, there it comes — that’s all. It’s awful, awful, awful.”

The big policeman in the door stepped to one side, and men came out bearing a litter, on which lay a grim, grisly something that had been a man. It was covered with a sheet. Beside it were Detective Mallory and Medical Examiner Barry. The little knot of onlookers was silent in the presence of death.

The stranger looked, looked as if fascinated by the horrid thing which lay there, watched them put the litter into the police ambulance, heard the Medical Examiner give some instructions and then Detective Mallory reentered the house. The wagon drove away.

Turning suddenly, the stranger strode quickly down the avenue to the first corner. There he turned away and was swallowed up in the darkness. After a moment, from a distance, came the sound of a man’s footsteps, running.
2

Several newspaper men, among them Hutchinson Hatch, went over the scene of the crime with Detective Mallory. It was a square, corner room on the second floor. The furniture consisted only of a bed, a table, a wash stand, chairs, there was no carpet to cover the gaping cracks in the floor, no curtains on the two windows.

The building was old and poorly constructed. Here a part of the cornice was sagging and broken, there the walls were mouldy; the ceiling was blotched with smoke, over by the steam radiator rats had gnawed a hole big enough to put one’s fist in, the single-stemmed gas jet was grimy with dirt.

Of the two windows one was in the back wall and one in the side. Hutchinson Hatch trailed around the room with Detective Mallory. He saw that the two windows were securely fastened down with a sliding catch over the middle of the lower sash; there were no broken panes so that one leaving by the window might have reached in and fastened it after him.

Mr. Mallory explored the closet, but found only the things that belong to a poor man: clothing, an old hat, a battered trunk. There was no opening, the walls were solid. Then Mr. Mallory went to the door that had been smashed in. It was the only door except that of the closet.

There was no transom.

Mr. Mallory and the reporter looked at this door a long time. It had been fastened when the police came — barred with an iron rod from one side to the other — held in round, iron sockets, set in the door facing. Neither of the sockets was open at the top; the bar had to be pushed through one straight on across the door into the other.

Thus early in the investigation Hutchinson Hatch saw this problem. If the windows were fastened inside and the murderer could not have passed out that way; if the door was fastened inside with an iron bar in both sockets and the murderer could not have gone that way — What then?

Hatch thought instinctively of a certain scientist and logician of note. Professor Augustus S.

F. X. Van Dusen, Ph. D., M. D., LL. D., etc., so-called The Thinking Machine, whom he had occasion to know well because of certain previous adventures in which the scientist had accomplished seemingly impossible things.

“And I think this would stump even him,” Hatch said to himself with a grim smile.

Then he listened as Detective Mallory questioned the various tenants of the house. Briefly the detective brought out these facts:

A man, whose description the detective carefully noted, had called to see Boyd that evening about half past eight o’clock. He had been there many times before. Four persons had seen him this evening in Boyd’s room, but no one of these knew his name. Some one passing had seen Boyd playing cards with him.

Shortly after 10 o’clock, when practically every one in the house had gone to bed, a man and woman in the next room heard Boyd’s voice and that of his caller raised suddenly as if in argument. This continued for five minutes or so, then it quieted down. Such things were common in the tenement and the man and woman dropped off to sleep, thinking nothing of it.

Some time later, evidently only a few minutes, they were awakened by that pitiful, terror-stricken cry which made them shudder. With others in the house who had been aroused they dressed hurriedly. It was then they heard heavy foot steps in the hall below and the street door opened with a bang.

Both were of the opinion not five minutes could not have elapsed from the time they heard the cry until they stood outside the door where the man lay. They would have heard, they thought, anyone leave Boyd’s room after they were awakened by the cry, yet there was no sound from there when they stood in the hall. Then they heard — what?

“It was a peculiar sound,” the man explained. “It struck me first that it was the swish of silk skirt, then, of course, as no woman was in the room, it must have been the dying man breathing.”

“Silk skirt! Woman! woman! wedding ring!” Hatch thought. Whose was it? How could a woman have escaped from the room when it seemed that it would have been impossible for a man to escape? The questionings concluded, Detective Mallory turned graciously to the representatives of the press who were waiting impatiently. It was after midnight, dangerously near the first edition time, and the reporters were anxious for the detective’s comment.

He was about to begin when another reporter, one of Hatch’s fellow workers, entered, called Hatch to one side and said something quickly. Hatch nodded his head and idly fingered a pack of playing cards he had taken from the table.

“Good,” he said, “Go back to the office and write the story. I’ll ‘phone Mallory’s statement and tell him that other thing. I want to do a little more work, but I’ll be at the office by halfpast 2 o’clock.”

The reporter went out hurriedly.

“I suppose you boys want to know something about how all this happened?” the detective was saying. He lighted a cigar and spread his feet wide apart. “I’ll tell you all I can — not all I know, mind you, because that wouldn’t be wise, but how the murder happened, and you can put in the thrill and all that to suit yourself.

“About halfpast 8 o’clock tonight a man called here to see Boyd. He knew Boyd very well — was probably a friend of several years’ standing — and had called here frequently. We have an accurate description of him. He was seen by several persons who knew him by sight, therefore will be able to absolutely identify him when we arrest him.

“Now, those two men were together in this room for possibly two hours. They were playing cards. More than half the murders on record are committed in the heat of passion. These men quarrelled over their game, probably ‘pitch’ or ‘casino’—”

“It’s a pinochle pack,” said Hatch.

“Then the crime was committed,” the detective went on, not heeding the interruption, “the unknown man was sitting here,” and Mallory indicated an overturned chair to his right.

“He leaped like this,” and the detective, with a full eye for dramatic effect, illustrated, “seized Boyd by the throat, there was a struggle, notice the other overturned chair — and the unknown man bore Boyd down gripping his throat. He choked him to death.”

“I thought the dead man was undressed when he was found?” asked Hatch. “The bed, too,” and he indicated its disordered condition.

“He was, but — but it must have happened as I said,” said the detective. He didn’t like reporters who asked embarrassing questions. “His victim dead, the murderer went out by that door,” and he pointed dramatically.

“Through the keyhole, I suppose?” said Hatch, quietly. “That door was fastened inside as no mere mortal could fasten it after he left the room.”

“It’s an old burglar’s trick to fasten a door after you leave the room,” said the detective, loftily.

“How about the wedding ring?”

“Ah!” and the detective looked wise. “There’s nothing to be said of that now.” He saw suddenly that he had made one mistake and he felt his prestige slipping away. The reporters turned a flood of questions upon him: “How did it happen Boyd was undressed?”

“Who put out the gas?”

“How would a burglar replace an iron bar like that?”

“Do you suspect a burglar?”

Mr. Mallory raised his hand. “I will say absolutely nothing else about the case.”

“Let’s see if we understand you,” said Hatch, and there was a mocking smile on his lips. “The police theory briefly is this: A man came here, there was a quarrel, a struggle; Boyd was killed, choked; then the murderer left this room by that door, possibly through the keyhole or a convenient crack. Then, being dead, Boyd got up, took off his clothes, turned out the gas, lay down on the floor, screamed for help and died again. Is that right?”

“Bah!” thundered Mr. Mallory, on the verge of apoplexy. “Perhaps,” he added scornfully, “you know more about it than I do.”

“Well, yes, I’ll confess that,” said Hatch. “I know at least the name of the man who was here tonight, and these other reporters will know it when their outside men come in.”

“You do, eh,” demanded Mr. Mallory. “Who is it?”

“His name is Frank Cunningham, a watchmaker of No. 213 — Street.”

“Then he is Boyd’s murderer,” Mr. Mallory declared. “We’ll have him under arrest in an hour.”

“He has disappeared,” said Hatch, and he left the room.
3

From the South Boston tenement house Hutchinson Hatch went to the undertaking establishment where the body of Fred Boyd lay, made a careful examination of the mark which showed that he had been throttled, and then went in a cab to the home of Professor Van Dusen, The Thinking Machine. As he drove up he noticed a bright light in the professor’s laboratory. It was just fifteen minutes past 1 o’clock when he ascended the steps.

The Thinking Machine in person answered the door bell, the leonine head with its shock of yellow hair, the clean shaven face, and the perpetually squinted eyes behind thick glasses standing out boldly and grotesquely in the light from a nearby arc.

“Who is it?” asked The Thinking Machine.

“Hutchinson Hatch,” said the reporter. “I saw your light and I was particularly anxious for a little advise, so I thought —”

“Come in,” said the scientist, and he extended his long, slender fingers cordially.

Hatch followed the thin, bowed figure of the scientist, which seemed that of a child, into the laboratory where he was motioned to a seat. Then Hatch told the story of the crime, so far as it was known, while the professor sat squinting steadily at him, his long taper fingers pressed together.

“Did you see the man?” asked The Thinking Machine.

“Yes.”

“What kind of marks, exactly, were those on his neck?”

“They seemed to be such marks as would be made by a large rope drawn about the throat.”

“Was the skin broken?”

“No, but whoever strangled him must have had tremendous strength,” said the reporter. “The pressure seemed to have been all around.”

The Thinking Machine sat silent for several minutes.

“Door fastened inside with iron bar,” he mused, “and no transom, so the bar was not placed back in position. Both windows fastened inside.”

“It would have been absolutely impossible for any person to leave that room after Boyd was dead,” said the reporter, emphatically.

“Nothing is impossible, Mr. Hatch,” said The Thinking Machine, testily. “I thought I had demonstrated that clearly, once. The worst anything can be is extremely difficult — not impossible.”

Hatch bowed gravely. He had walked over one of The Thinking Machine’s pet hobbies.

“Man was undressed,” went on The Thinking Machine. “Bed disordered, chairs overturned, gas out.” He paused a moment, then asked: “You reason that the man must have gone to bed after putting out the light, and that his murderer came upon him unawares?”

“That seems to be the only possible thing to imagine,” said Hatch.

“And in that case the other man — Cunningham — would not have been there?”

“Precisely.”

“What sort of a wedding ring was it?”

“Perfectly new. It didn’t seem to have ever been worn.”

The Thinking Machine arose from his seat and took down a heavy volume, one of hundreds which lined his walls.

“You don’t believe it probable that Cunningham left the room while angry and returned after Boyd was asleep and killed him?” asked The Thinking Machine as he fingered the leaves.

“He couldn’t have come back if that door was fastened,” said Hatch, doggedly.

“He could have, of course,” said The Thinking Machine, “but it is hardly probable. Do you think it reasonable to suppose then that someone hidden in the closet waited until Cunningham was gone and then killed Boyd?”

“That sounds more plausible,” said Hatch, after a moment’s consideration. “But he couldn’t have gone out of that room and fastened the door or window behind him.”

“Of course he could have,” said The Thinking Machine, irritably. “Don’t keep saying he couldn’t have done anything. It annoys me exceedingly.”

Properly rebuked Hatch sat silent while The Thinking Machine sought something in the book.

“In the event, of course, that somebody was hidden in the room it would make it a premeditated murder, wouldn’t it?” asked the scientist.

“Yes, unquestionably,” replied the reporter.

“Here is something,” said The Thinking Machine, as he squinted into the volume he held. “It is logic reduced to figures. Criminologists agree, practically, that thirty and one-third per cent of all premeditated crimes are committed because of money, directly or indirectly; that two per cent are committed because of insanity; and that the others, sixty-seven and two-thirds per cent, are committed because of women.”

Hatch nodded.

“We’ll shut out for the time being the matter of insanity — it is only a remote chance; money would hardly enter into the case because of the fact that both men were poor. Therefore, there remains a woman. The wedding ring found in the room also indicates a woman, though in what connection is not clear.

“Now, Mr. Hatch,” he continued, glaring at the reporter almost fiercely, “find out all you can about the private life of this man Boyd — it will probably be like every other man of his class — and particularly his love affairs; find out also all you can about Cunningham and his love affairs. If the name of any woman appears in the case at all, find out all about her — and her love affairs. You understand?”

“Yes,” was the reply.

“Don’t delude yourself with the thought that it was impossible for anyone to leave that room after Boyd was dead,” went on the scientist, with the stubborn persistence of a child. “Suppose this — I don’t offer it as a solution — suppose that Boyd had been engaged to be married, that someone else loved the girl he was to marry, that that someone else had hidden in his room until Cunningham went away, then — you see?”

“By George!” exclaimed the reporter. “I never thought of that. But how did he get out?” he added helplessly.

“If a man did do such a thing he would have made every arrangement to leave that room in a manner calculated to puzzle anyone who came after. Mind, I don’t say this is what happened at all — I merely suggest it as a possibility until I find more to work on.”

Hatch arose, stretched his long legs and thanked The Thinking Machine as he pulled on his gloves.

“I’m sorry I could not have been of any more direct assistance,” said the scientist. “When you do these things I ask come back to see me — I may be able to help you then. You see I’m at a tremendous disadvantage in not having seen the place where Boyd was killed. There is one thing, though, which I particularly would like for you to find out for me now — tonight.”

“What is it?” asked Hatch.

“This tenement is an old building, I understand. I should like to know if the occupants have ever been annoyed by rats and mice, and if they are so annoyed now?”

“I don’t quite see —” began the reporter in surprise.

“Of course not,” said The Thinking Machine petulantly. “But I should like to know just the same.”

“I’ll find out for you.”

Hutchinson Hatch had still nearly an hour, and he drove to the tenement in South Boston, to wake up its occupants and ask them — of all the silly questions in the world —“Are you annoyed by mice?” He set his teeth grimly and smiled.

When he reached the tenement he went straight on to the second floor. The steps ended within a few feet of the door where the crime had been committed. Hatch looked at the door curiously; the police had gone, the room was silent again, hiding its own mystery.

As he stood there he heard something which startled him. It came from the room where Boyd had been found dead. There was no question of that. It was a faint whispering sound as of wind rustling through dead leaves, or the silken swish of skirts, or the gasp of a dying man.

With blood tingling, Hatch rushed to the door and threw it open. He stepped inside, lighting a match as he did so. The room was empty save for the poor furniture. No sign of as living thing!
4

Straining his ears to catch every sound, Hatch stood still, peering this way and that until the match burned his fingers. Then he lighted another and still another, but there was no repetition of the noise. At last the ghostly quiet of the room, its gloom and thoughts of the mystery which its walls had witnessed began to press on his nerves. He laughed shortly.

“A very pronounced case of enlargement of the imagination,” he said to himself, and he passed out. “This thing is getting on my nerves.”

Then, feeling very foolish, he aroused several persons and inquired solicitously as to whether or not they had ever been troubled with mice or rats, and when this annoyance had stopped, if it had stopped.

The concensus of opinion was that it was a silly thing to ask, but that up to a fortnight ago the rodents had been very bad. Since then no one had noticed particularly. These things, in so far as they related to rodents of any kind, were telephoned to The Thinking Machine.

“Uh, huh,” he said over the ‘phone. “Thanks. Good night.”

From that point on every effort of the police and the press was directed to finding Frank Cunningham, who was openly charged with the murder of Fred Boyd. His disappearance had been complete. If there had been any doubt whatsoever of his guilt, this was convincing — to the police.

It was Hatch’s personal efforts that uncovered the fact that Cunningham had had a bank account of $287 in a small institution, that on the morning following the mysterious crime in the South Boston tenement a check to “cash” had been presented for the full sum and that check had been honored. This began to look conclusive.

It was also due to Hatch’s personal efforts that the police learned Cunningham was to have been married a week after his disappearance to Caroline Pierce, a working girl of the West End. Then Hatch discovered that Caroline Pierce had also disappeared; that she went away presumably to work on the morning after the murder of Boyd. Where had she gone? No one knew, not even Miss Jerrod, the girl who, with her, occupied a suite of three rooms in the West End. Why had she gone? No one knew that. When had she gone? Still no one knew. When would she return? Again the same answer.

To the reporter there seemed only one plausible explanation. This was that Cunningham had drawn his money from the bank — which he had saved to make a little home for the girl he loved — and they had gone away together. In the natural course of his duty Hatch printed this, and it came to the eyes of the police. Detective Mallory smiled.

But the wedding ring in Boyd’s room?

There was no explanation of that. Boyd had had no love affair so far as any one knew. He had been a hard-working, steady-going man in his trade — electrician employed by a telephone company — and he and Cunningham had been friends since boyhood.

All these things, while interestin............