"Hands up!" he cried, and Pollock turned to see a small but dauntless-looking boy threatening him.

Again endangered by his own firearm, Pollock stood at bay, raging but impotent in the face of the steady aim of the boy.

In another moment Stone came, with Campbell, in the Pell car and Iris breathed freely once more, as she felt stealthily for the pin in her belt ribbon. It was safe, and she sank down on the ground, satisfied to let the newcomers take charge of the whole matter.

This they did with neatness and dispatch.

Bidding Fibsy keep the two men covered with the small but efficacious weapon, Stone and Campbell tied the hands of Pollock and his man Bob, using the dustrobe from Pollock's car, cut into strips for the purpose.

Then they bundled them unceremoniously into their own car and Stone himself took the wheel.

Campbell drove Iris home, but Fibsy traveled with his chief.

The boy was thrilling with satisfaction at the way things were turning out, and not at all vain-glorious over his own part in the affair.

Stone turned the two men over to the police on a charge of kidnapping and then, elated, returned to Pellbrook.

"How can I be grateful enough to you," Iris cried at sight of the detective, "for coming to my aid! And Fibsy, too! Oh, what should I have done if you hadn't arrived just as you did? But how did you know where we were?"

"I didn't," said Stone; "it was Fibsy's idea that the man would take to the woods. But your screams and the noise of the revolver led us at the last. I congratulate you, Miss Clyde, on a pretty narrow escape. Those men were desperate."

"Oh, I know it! Pollock began by being fairly courteous, but when I wouldn't give up the pin, he grew rough and rude."

"Miss Clyde, we must look out for that pin. Though, now that the one who wants it is in safe-keeping himself, there's not so much danger. But he may have clever a.s.sistants. By the way, there's no doubt that this so-called Pollock is Charlie Young. Hughes is putting him through a third degree, and I think we need not concern ourselves about him just now. He won't escape from his present quarters easily."

"This child must go to bed now," said Lucille Darrel, with an affectionate glance at Iris. "She's had enough to upset any ordinary set of nerves, and she must rest."

"Yes, Miss Clyde, go now, and I think, if you leave the pin with me I'll keep it safely, and moreover, to-morrow morning, I'll tell you its secret."

"Oh, tell me now! Please do, Mr. Stone. What can it be that makes it a key to the jewels' hiding-place?"

"Not to-night. Indeed, I don't yet know its secret myself, but I hope to find it out. If I may, I'll stay alone in Mrs. Pell's sitting-room for a time, until I puzzle it out."

Iris reluctantly went off with Lucille, and the detective locked himself in the room where Mrs. Pell had met her tragic death.

He had, as his working implements, the pin, a strong magnifying gla.s.s, a thick pad of paper and a lead pencil.

As the first streaks of dawn began to show in the eastern heavens, Fleming Stone had, as results of his night's work, forty or fifty scribbled pages of the pad, all of which were in the waste basket, a small, remaining stub of lead pencil and the pin and the magnifying gla.s.s.

Also he had a heavy heart and a feeling of despair and dejection.

He went to his room for a few hours' sleep before breakfast time and when he met the family at table, he said shortly, "Finding a needle in a haystack is child's play compared to the task ahead of us."

He refused to explain until after breakfast, and then, Iris and Lucille went with him to the sitting room and the door was closed upon them.

Fibsy was there, too, as the boy was never excluded from important conferences.

Stone locked the door, and then said, impressively, "The dime and pin bequeathed you by your aunt, Miss Clyde, form a far more valuable inheritance than any diamond pin I have ever seen. I congratulate you on the possession of the pin, and I ask you where the dime is."

"Gracious, I don't know," replied Iris. "I threw it out of the window the day I received it, and I've never thought of it since."

"The pin is a key to the hiding-place of the jewels, as I will explain fully in a few minutes," Stone proceeded, "but it may be necessary to recover the dime also, before we can utilize the information given us by the pin."

Iris looked bewildered, but repeated her statement as to the whereabouts of the dime.

"And again," Stone said, "the dime may be of no importance in the matter. I'm inclined to think it is not, because Pollock--or Young rather--made no effort to gain possession of the dime, did he?"

"No; I think not. That first day he called on me, as Mr. Pollock, and wanted the pin, I told him he might search the lawn for the dime if he chose, but I don't think he did so."

"I'll find the dime if it's out in the side yard," Fibsy volunteered.

"Now, I'll tell you what this pin is," resumed Stone, holding up the mysterious bit of bra.s.s. "It contains a cipher--a cryptogram."

"How can it?" asked Iris, blankly.

"On the head of this pin is engraved a series of letters which form a cipher message telling of the hiding-place of your aunt's jewels."

"On the head of that little pin! Impossible!"

"It does seem impossible, but I a.s.sure you that on the surface of the head of this pin there are thirty-nine letters, which, meaningless in themselves, form a cipher statement. If we can solve their message----"

"If we _can_!" cried Iris. "We _must_!"

"You bet Mr. Stone will work it out, if it's a cipher," Fibsy declared, looking with pride and confidence at his employer's face.

"Not so easy, Fibs," Stone returned. "It's a cryptogram which necessitates another bit of information, a keyword, before it can possibly be solved. By the way, Miss Clyde, that's what your aunt's diary means by its reference to the jewels being hidden in a crypt. If you read her diary carefully, you'll see that she very frequently abbreviates her words, not only Tues., for Tuesday, and Dec., for December, but other words, just as the whim took her. So, as we may conclude, the word crypt stands for cryptogram. And here's the cryptogram. Now, to explain this seemingly miraculous feat of engraving thirty-nine letters on the head of an ordinary pin, I'll say that it is not an unheard-of accomplishment. Several years ago, I saw on exhibition a pin with forty-five letters to it, and I have seen one or two other similar marvels. They are done, in every instance, by a most expert engraver, who has much time and infinite patience and capacity for carefulness. Indeed, it is an art all by itself, and I doubt if there are many people in the world who could accomplish it at all."

"Can you show them to me?" Iris asked, her eyes wide with wonder.

"Oh, yes, you can see them with this gla.s.s, though even with its aid you may have difficulty in making out the letters."

Iris looked long and carefully through the powerful lens, and finally declared that she could discern the letters, but could not read them clearly.

Stone pa.s.sed the pin and gla.s.s to Miss Darrel, and continued, "I spent nearly the whole night over it. I have copied off the letters, so now, if the pin should be stolen, at least we have its secret. Though, I confess the secret is still a secret."

"Lemme see it," begged Fibsy, as Miss Darrel gave up the effort to make out the letters at all.

The younger eyes of the boy read them with comparative ease.

"O, I, N, V, L, D, L," he spelled out "Sounds like gibberish, but all ciphers do that--why, Mr. Stone, the letters are clear enough and you can read any cipher that ever was made up, I'll bet! You know, you first see what letter's used most, and that's E----"

"Hold on, Terence, not so fast. That's one kind of a cipher, to be sure. But this is another sort. These are the letters:

"O I N V L D L Q P S V T H P J R C R N O X X I V B A Y O D I J Y A W W K M E U

"There's no division into words, which, of course, makes it infinitely more difficult."

"Aunt Ursula was crazy over ciphers!" exclaimed Iris, "she was always making them up. But she always called them ciphers, never cryptograms, or perhaps I might have thought that crypt. was an abbreviation. But can't you guess it, Mr. Stone?"