Fleming Stone carried his years lightly. Except for the slight graying at his temples, no one would think that he had arrived, as he had, at the years that are called middle-aged.

But an especially interesting problem so stirred his enthusiasm and roused his energies that he grew young again, and his dark eyes fairly scintillated with eagerness and power.

"Tell me everything," he repeated, even after he had heard all the details over and over again. "Omit nothing—no tiniest point. It all helps."

They sat in the living room at Pellbrook, Miss Darrel and Iris being present, also Hughes and Lawyer Chapin.

Stone had examined the sitting room where Mrs. Pell had died, and, closing its door, had returned to the big living room, for further information on the whole subject of the crime and its subsequent events.

"The pin's the thing," he said, at last. "Everything hinges on that."

"Do you think so?" asked Mr. Chapin. "It seems to me the pin's a blind—a decoy—and the people hunting it are really after something else, of intrinsic value."

Fleming Stone looked at the lawyer, with a courteous impatience.

"No, Mr. Chapin, the pin is the thing they are after. It was for that pin that Mrs. Pell was murdered. That is why her dress was torn open at the throat, the villain was searching for that pin. That's why the desk was ransacked, the handbag explored, the pocket-book emptied—all in a desperate effort to find that seemingly insignificant pin! That is why the poor woman was tortured, maltreated, bruised and beaten, in final attempts to make her tell where the pin was. Failing, the wretch flung her to the floor, in a burst of murderous frenzy."

"That's why I was kidnapped, then," exclaimed Iris.

"Of course, and you may be again! Those people will stop at nothing! The letters asking for the pin, the caller who wanted it for his 'collection,' all represent the same master-mind, who is after the pin.

"But why?" wondered Hughes, "what do they want of the pin?"

"The pin means the jewels," declared Stone, briefly. "How, I can't say, exactly, for the moment, but the pin is the open sesame to the hiding-place of the gems, and only the possession of it will secure the treasure. We must get the pin—and then, all else will be clear sailing."

"But the pin is gone," lamented Iris.

"That is the worst phase of it all," Stone said, regretfully. "It is such a difficult thing to trace—not only so tiny, and easily lost, but so like thousands of others, that it can't readily be discerned even if seen."

"You think it's just an ordinary pin, then?" inquired Chapin.

"Absolutely, sir."

"Then why won't any other pin do as well?"

Stone looked at him keenly. "I can't answer that at present, Mr. Chapin; my theory regarding the pin, while doubtless the truth, is as yet uncertain. Now, another and equally great problem is that of the murderer's exit. From your story of the crime, I gather that the room was absolutely unenterable, except by breaking in the door, which Purdy and the chauffeur did?"

"That is true," agreed Iris; "the windows, as you can see, are strongly barred, and there is but the one door. Search has been made for secret entrances or concealed passages, but there is nothing of the sort."

"No," said Stone, "this sort of a house is not apt to have such. If there were any, they would be easily discovered. And there were several people in this room, when the two men burst in the door?"

"Yes," said Iris. "I was here, and Polly, the cook, and the two men——"

"You are positive the murderer could not have slipped by you all, as the door flew open, and so made his escape?"

"That was utterly impossible. We were all grouped around the door and stayed so, until we entered the sitting room ourselves. There was nobody there but Aunt Ursula, herself——"

"Dead?"

"Yes, but only just dead. Polly heard her faint moans, after her loud screams, you know, before we broke in."

"And what were the words she used when she screamed out?"

"I don't know exactly, but they were cries for help, and I'm sure Polly said she called out 'Thieves!' Of course, she was unable to speak coherently."

"Now," began Stone, "to look at this one point. Her assailant had to get out or stay in, didn't he? You're sure he didn't get out, therefore he must have stayed in. A man of flesh and blood cannot go through walls, like a ghost."

"But he didn't stay in!" cried Iris. "We searched the room at once, there was nobody in it. You know there's almost no place to hide. We looked behind the window curtains, and all such places—and, too, we were in this room continuously, till others came, and no one could have gone through here without being seen."

"Nor could he get out of the barred windows. Then what became of him?"

"Ah, Mr. Stone," said Hughes, "that's the question that has puzzled us all. If you can solve that, we can begin to look for the murderer!"

"Meantime, we must assume him to be a spook? Is that it?" Stone smiled a little at the complacent Hughes.

"I don't say that, but I do call the manner of his exit an insoluble mystery."

"If he could accomplish it, I can find out how," Stone said, quietly. He had no air of bravado, but he made the statement in all sincerity.

"I believe you can!" declared Lucille. "That's why I wanted you, Mr. Stone. I've heard of your almost unbelievable cleverness, and I knew if anybody could get to the bottom of this mystery, you could."

"I don't mind admitting that it is seemingly the most inexplicable one I ever encountered, but I shall do my best. And I want the coÖperation of you all. There are many things to be told me yet; remember I've only just heard the main details, and each of you can give me light in different ways. I'll call on you for information when necessary. Also, Miss Darrel, will you extend your hospitality to my young assistant?"

"That boy?" Lucille smiled.

"Yes; Terence, his name is. He's my right-hand man and attends to a lot of detail work for me."

"He's a handful," and Lucille laughed again. "I saw him in the kitchen, wheedling round Polly, and begging for cookies."

"I'll warrant he got 'em," said Stone. "He has a way with him that is persuasive, indeed. But he won't make you any bother. Fix him up a bed in the loft, or anywhere. He's willing to rough it."

"Oh, no, he can have a decent room, of course. I'll give him one in the garage, there's a nice one next to Campbell's."

At that moment, Terence appeared at the door.

"Come in," said Stone. "I want these ladies to know you."

Awkwardly the boy entered, and blushed furiously as Stone gravely introduced him all round.

"We'll be friends, Terence," said Iris, who felt sorry for his embarrassment, and who pleasantly offered her hand.

"Thank you, ma'am, and will you please call me Fibsy, it makes me feel more at home—like."

"Fibsy! What a funny name! Because you tell fibs?"

"Yes'm! How'd you guess?" The laughing eyes met hers and the boy's stubby paw touched Iris' soft hand.

But some subtle spark passed between them, that made each feel the other a friend, and a tacit compact was sealed without a word.

"Lemme see the room?" whispered Fibsy, with a pleading look at Fleming Stone.

"Yes," and the detective rose at once, and accompanied the lad to the room of the tragedy.

The details of the death of Mrs. Pell were quickly rehearsed, and Fibsy's eyes darted round the room, taking in every detail of walls and furniture.

Hughes was astounded. Who was this insignificant boy that he should be consulted, and referred to? Why was an experienced detective, like himself, set aside, as of no consequence, while Fleming Stone watched absorbedly the face of the urchin?

"How did the murderer get out?" Hughes could not help saying, with a view to confusing the boy.

"Gee! If all you local police has concentrated your thinkers on that all this time, and hasn't doped it out yet, I can't put it over all at once! But Mr. Stone, he'll yank the heart out o' the mystery, you can just bet. Of course, 'How'd the murderer get out?' is easy enough to sit around an' say—like a flock of parrots! The thing to do is to find out how he did get out!"

Fibsy stood, hands in pockets, in front of the mantel, looking down at the floor.

"Here's where she was lyin'?" he asked gravely, and Iris nodded her head.

Leaning down, Fibsy looked up the chimney, and Hughes laughed out.

"Back number!" he said, looking bored, "Don't you s'pose we've investigated that chimney business? A monkey couldn't get up that little flue, let alone an able-bodied man!"

"That's so, my bucko!" and Fibsy beamed on Hughes, without a trace of rancor at the elder man's scorn.

"Now about the evidence against Mr. Bannard," Stone said to the local detective, "do I understand it's only the newspaper and cigarette that he was supposed to have left in this room——"

"Well," Hughes defended himself, "he had motive, he was seen around these parts, and he denies he was up here——"

"Never mind, I'll talk with him, please. I'll learn more from his own story."

"He isn't guilty, oh, Mr. Stone, he isn't guilty!" Iris exclaimed, her beautiful eyes filling with tears. "Please get him out of that awful jail, can't you?"

"Let us hope so, Miss Clyde." Stone spoke abstractedly. "Where is the newspaper in question?"

"Here it is," and Iris took it from a drawer and handed it to him.

"Why, this has never been opened," exclaimed Stone.

"No," agreed Hughes, "when Bannard came up here Sunday morning on his bicycle, he had no thought for the day's news! He had other plans ahead. He carried that paper up here without reading it, and he left it here, also unopened."

"Might 'a' been opened an' folded up again," offered Fibsy. "It has, too."

"I did that," said Hughes, importantly. "I opened it, the first time I saw it, naturally one would, and I refolded it exactly as it was. It's of no further value as evidence, but I made sure it hadn't been read. You can always tell if a paper's been read or not."

"Sure you can," agreed Fibsy. "Where's this Mr. Bannard live?"

"In bachelor apartments in New York," said Iris.

"I mean, where in New York?" the boy persisted

"West Forty-fourth Street."

"He ain't the murderer," and Fibsy handed the newspaper, that he had been glancing over, back to Hughes.

"You darling!" cried Iris, excitedly, grasping Fibsy's two hands. "Of course he isn't. But how do you know?"

"Don't go too fast, Fibs," said Fleming Stone, smiling with understanding at the boy. "Shall we say the real murderer lives somewhere near Bob Grady's place?"

"Yes, sir, yes! O Lord, what a muddle!"

Again the boy stood in front of the fireplace, musing deeply.

"New?" he said, turning to the electric lamp on the nearby table.

"Yes," said Iris, puzzled at his actions. "When the man knocked Auntie down the table was overturned and the lamp smashed to bits. We put a new one in its place."

"Oh, all right. Now where was that cigarette stub found, and how far was it burned?"

Hughes disliked to answer the boy's questions, but Fleming Stone turned expectantly toward him, so he replied, "It was on the desk, and it was about half-smoked."

"And this poker? Did it lie here, where it is now? Wasn't she hit with it?"

"Those things have all been thrashed out," replied Hughes, a little petulantly. "No, she wasn't hit with the poker, she was flung down and her head knocked onto the sharp knob on the fender."

"How do you know?"

"There's a blood stain on the brass knob, and her head was right by it. The poker is two feet away."

"Might 'a' been used, all the same," and Fibsy stared at it. "Howsumever, that don't count. We've got her dead, and we've got to find out who did it—and, so far, it wasn't Mr. Bannard."

"When will it begin to be Mr. Bannard?" said Hughes, with fine sarcasm.

"I mean," Fibsy returned, quietly, "so far, they ain't nothin' to implicate Mr. Bannard. Somethin' might turn up, though. But I don't think so. And anyway, the problem, first of all, ain't who, but how. That's what we must hunt out first, eh, Mr. Stone?"

"Very well, Terence," Stone spoke abstractedly, "you attend to that, while I find the pin. It seems to me that is the most important thing——"

"Ain't that F.S. all over!" cried Fibsy, admiringly. "Puts his finger on the very spot! An' me a babblin' foolishness about findin' how the chappie got in!"

"You do certainly babble foolishness," flung out Hughes, unable to conceal his annoyance at the boy's forwardness, as he looked upon it.

"Yes, sir," and Fibsy's humble acceptance of Hughes' reproof had no tinge of irony. The boy was not conceited or bumptious, he was Stone's assistant, and took no orders save from his chief, but he never assumed importance on his own merit, nor behaved with insolence or impertinence to anyone. His only desire was to serve Fleming Stone, and an approving nod from the great detective was all the reward Terence Maguire desired.

And then, Fibsy seemed possessed of a new idea of some sort, for with a sudden exclamation and a word of excuse he ran from the room.

"Don't allow yourself to be annoyed by that boy, Mr. Hughes," said Stone; "he is a great help to me in any work. His manners are not intentionally rude, but sometimes he gets absorbed in an investigation, and he forgets what I've tried to teach him of courtesy and consideration for others. He's of humble birth, but I'm endeavoring to make him of gentlemanly behaviour. And I'm succeeding, on the whole, but in emergency the fervor of his soul runs away with the intent of his mind. For he wants to behave as I ask him to, I know that. Therefore, I forgive him much, and I must ask you to be also lenient."

Then, apparently feeling that he had done his duty by Hughes, the detective turned his attention to the room once more.

He scrutinized everything all over again. He left no minutest portion of the mantel, the table, the desk or the window draperies uninspected. A few taps at walls and partitions brought the comment, "No secret entrance, and had there been, you people must have found it 'ere this. It is a satisfaction to find so much of the investigating done already—and thoroughly done."

Hughes bridled with satisfaction, and eagerly watched Stone's further procedure.

Fibsy took his way to the garage, and began a desultory conversation with Campbell, the chauffeur.

"Who's the college perfessor?" he asked, pointing a thumb over his shoulder at a long, lank figure, hovering toward them.

"Him? He's Sam."

"Sam?"

"Yep."

"Don't babble on so! I don't want all his family history. Quit talking, can't you?"

As Campbell had said only a few monosyllables, and as he had the Scotchman's national sense of humor, he merely stared at his interlocutor.

"Oh, well, since you're in a chattering mood, spill a little more. Who's he, in America?"

"Sam? Oh, he's Agnes' half-brother, and he's half-witted."

"H'm. Sort of fractional currency! Is he—is he exclusive?"

"Eh?"

"Never mind, thank you. I'll be my own intelligence office. Hey, Sam, want some chewin' gum?"

The lackwit turned to the bright-faced boy who followed him, and favored him with a vacant stare.

"Gum, sonny, gum, you know. Chew-chew! Eh?"

Sam held out his hand, and Fibsy put a paper package in it.

"Wait a minute," he went on, leading Sam out of earshot of the garage. "What's that song I heard you singing a bit ago?"

"No, sir! Sam don't sing that more."

"Oh, yes, Sam does. It's a pretty song. Come now, I like your voice. Sam sings pretty—very pretty."

The wheedlesome tone and smile did the trick, and the foolish boy broke out in a low, crooning song:

"It is a sin to steal a pin,
As well as any greater thing."

"Good!" Fibsy applauded. "Where'd you learn that, Samivel?"

"Long ago, baby days."

"And why do you sing it to-day?"

A look of fear came over Sam's face, followed by a smile of cunning. He looked like a leering gargoyle, as grotesque as any on Notre Dame.

"You know why?" he whispered.

"Oh, yes, I know why. But we won't tell anybody, will us?"

"No, not anybody."

"Who'd you steal it from?"

"From chair, he, he! From old Mister Chair."

"Yes, of course," and Fibsy's heart beat fast. "The big, fat Mister Chair?"

"Yes, big fat Mister Chair!"

"In Mrs. Pell's room?"

"Yes, yes, in Missy Pell's room."

But Fibsy began to think the clouded intellect was merely repeating words spoken to it, and he asked, "Who put pin in chair for Sam to steal?"

"Who?" and the blank, foolish face was inquiring.

"Campbell?"

"No, no! not Campbell!"

"No, no, it was Agnes."

"No! not Agnes——"

"Who, then?" Fibsy held his breath, lest he disturb the evident effort the poor lad was making to remember.

"Missy Iris," Sam said at last, "yes, Missy Iris, Missy Iris—yes, Missy——"

"There, there," Fibsy shut him up, "don't say that again. Did you see her?"

"Yes, by window. Then, Sam steal pin. It is a sin to steal a pin. It is a sin to steal a pin—it is——"

But Fibsy set to work to turn the poor befuddled mind in another direction, and after a time he succeeded.