"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-to-night."
"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!
IV.
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 interesting in themselves, still threw no light on the actual crime. Who killed Boyd, and why? How did the murderer get away? Hatch had put the question to himself time and again. There was no answer. Thus the intangible pall of mystery which lay over the happenings in the South Boston tenement was still impenetrable.
On the second day after the crime Hatch again consulted The Thinking Machine. The scientist listened patiently and carefully, but without any enthusiastic interest to the reporter's recital of what he had discovered.
"Have you a man watching the place where the girl lives?" he asked.
"No," Hatch replied. "I think she's gone for good."
"I don't think so," said The Thinking Machine. "I should send a man there to see if she returns."
"If you think best," said Hatch. "But don't you think now this man Cunningham must have been the criminal?"
The scientist squinted at the reporter a long time, seemingly having heard nothing of the question.
"It looks that way to me," Hatch went on, hesitatingly. "But frankly, I can't imagine a way that he might have left that room after Boyd was dead."
Still the scientist was silent, and the reporter nervously fingered his hat.
"That information you gave me about the rats was very interesting," said The Thinking Machine at last, irrelevantly.
"Perhaps, but I don't see how it applies."
"Looking out the windows of the room where Boyd was found, what did you see?" the scientist interrupted.
Hatch did not recall that he had ever looked out either of the windows; he had merely satisfied himself that neither had been used as a means of exit. Now he blushed guiltily.
"I'm afraid you haven't looked," said The Thinking Machine, testily. "I thought probably you wouldn't have. Suppose we go to South Boston this afternoon and see that room."
"If you only would," said Hatch, delightedly. Here was better luck than he dreamed of. "If you only would," he repeated.
"We'll go now," said The Thinking Machine. He left the room and returned a moment later dressed for the street. The slender, bent figure and the great head seemed more grotesque than ever.
"Before we go," he instructed, "telephone to your office and have a reliable man sent to watch the girl's house. Tell him under no circumstances to try to enter or speak with anyone there until he hears from us."
The Thinking Machine stood waiting impatiently while Hatch did this. Then they took a cab to the tenement in South Boston.
"Dear me, what an old, ramshackle affair it is!" commented the scientist as they climbed the stairs.
The door of Boyd's room was not locked. The furniture and the personal effects of the man had been moved out-taken in charge by the Medical Examiner for possible use at an inquest.
"Just how was this room fastened when Boyd was found?" asked the scientist.
Hatch showed him, at the door and windows. The Thinking Machine was interested for a moment and then looked out the side window. Straight down fifteen feet was a wilderness of ash barrels and boxes and papers-a typical refuse heap of a cheap tenement. Then The Thinking Machine squinted out the back window. There he saw an open space, a rough baseball diamond, intersected at two places by the trampled down rings of a circus.
Perfunctorily he peered into the closet, after which his eyes swept the room in one comprehensive squint. He noted the begrimed condition of the place; the drooping cornice, the smoky ceiling, the gaping cracks in the floor, the rat holes beside the radiator, the dirty gas pipe leading down to a single jet. He leaned against a wall and wrote for several minutes on a sheet of paper torn from his notebook.
"Have you an envelope?" he asked.