"But what shall I do?" seemed now to be the burden of her thought. At first she felt impelled to telegraph Ray to come and attend to the matter; then she feared the man and woman would both disappear before he could arrive, and she felt that some immediate action should be taken.

"I believe my best way will be to go directly to a detective, and tell him my story; he will know what ought to be done, and I can leave the matter in his hands," was her final conclusion.

She sped to her own room, secured a needleful of silk, then hastened back to Mrs. Walton's room and sewed the rent in the dress together once more, taking care not to fray the edges, lest the piece she had should not fit when it was examined again.

CHAPTER VIII.

MR. RIDER BECOMES ACTIVE AGAIN.

After hanging the dress again in its place, Mona quickly finished her work in the room, then went back to the girl whom she had left sleeping in one of the adjoining chambers, and awoke her.

She had slept nearly an hour, and, though Mona knew that she needed many hours more of rest, she was sure that she would be the better for what she had secured.

"You are very good, miss," she said, gratefully; "the pain is all gone from my tooth, and I feel ever so much better."

"Your sleep has quieted your nerves; but I advise you to see a dentist and have the tooth attended to," Mona returned; then hastened away to her room, where she dressed herself for the street and went out.

Mrs. Montague had been out for a long time driving with some friends.

Mona inquired of an elderly, respectable policeman, whom she found standing upon a corner, where she should go to find a detective.

He directed her to the headquarters of the force, although he looked surprised at the question coming from such a source, and she repaired thither at once.

As she entered the office, a quiet-looking man, who was the only occupant at that time, arose and came forward, bowing respectfully; but he also appeared astonished to see a young and beautiful girl in such a place.

"I wish to see a detective," said Mona, flushing hotly beneath the man's curious glance.

"The men connected with this office are all out just at this moment, miss. I am a stranger, and only sitting here for a half-hour or so, just to oblige the officer in charge," the man courteously replied.

"I am very sorry," said the young girl, with a sigh, "for I have come upon business which ought to be attended to immediately."

"I am a detective, miss, although I do not belong here. I'm an officer from New York; but if you see fit to tell me your business, perhaps I might advise you," said the officer, kindly, for he saw that she was greatly troubled.

"You are from New York!" Mona exclaimed, eagerly; "then perhaps it will be better for me to tell you, rather than a St. Louis detective; for the robbery happened in New York."

The detective's eyes flashed with sudden interest at this.

"Ah!" was all he said, however, and this very quietly.

"Yes, it was a diamond robbery. A dress worn by one of the persons connected with it was torn; a small piece was entirely cut out of it. I have found the dress; I have fitted the piece into the rent, and now I want the woman who owns it to be arrested and examined," Mona explained, in low, excited tones, but very comprehensively.

"Ah!" said the detective again, in the same quiet tone; "you have reference to the Palmer robbery."

Mona lifted a pair of very astonished eyes to his face.

"Yes," she responded, breathlessly; "but how did you know?"

"Because I am looking after that case. I am in St. Louis upon that very business," replied the man, with a twinkle in his eyes.

"Are _you_ Detective Rider?" questioned the young girl, wonderingly, and trembling with excitement.

Her companion smiled.

"What do you know about Detective Rider?" he inquired. Then, as she flushed and seemed somewhat embarra.s.sed, he continued: "And who are _you_, if you please?"

"I am--I am acquainted with Raymond Palmer," Mona answered, evasively; "he has told me about the robbery and--"

"Ah! yes. I understand," interposed the quick-witted officer, as he comprehended the situation. "But sit down and tell me the whole story as briefly as possible, and I can then judge what will be best to do."

He moved a chair forward for her, then sat down himself, where he could watch her closely, as she talked, and Mona related all that we already know regarding the two people whom she had seen upon the street-car, together with all that followed in connection with the discovery of the rent in the gray cloth dress, the sending for the fragment that Ray had preserved, and which had fitted so exactly into the tear.

The detective listened with the closest attention, his small, keen eyes alone betraying the intense interest which her recital excited.

When she had concluded, he drew forth a set of tablets and made notes of several items, after which he said:

"Now, Miss ---- What shall I call you? Whom shall I ask for at the hotel, if I should wish to see you again upon this business?"

"Miss Richards. I am traveling with a Mrs. Montague, of New York," Mona replied.

"Well, then, Miss Richards, you go back to your hotel, and of course conduct yourself as if you had nothing unusual on your mind; but hold yourself in readiness to produce that important bit of cloth, if I should call upon you to do so within the next few hours. By the way,"

he added, with sudden thought, "if you have it with you, I might as well take a look at it."

Mona took the paper containing it from her purse and gave it to him.

"You are _sure_ this matches the dress?" he asked, examining it closely.

"We don't want to make any awkward mistakes, you know."

"It is identical. I believe that every thread in this piece can be matched by a corresponding thread in the garment," the fair girl a.s.serted, so positively that he seemed to be entirely satisfied.

He returned the piece to her and then arose in a brisk, business-like way, which told that he was ready for action.

Mona also rose, and, bidding him a quiet good-day, went quickly out of the office, and hastened back to the hotel.

In order to understand more fully some of the incidents related, we shall have to go back a few days.

It was a bright, clear morning when a rather rough-looking, yet not unattractive person, entered a large jewelry establishment located on one of the princ.i.p.al streets of St. Louis.

He might have been thirty-five years of age, for there was a sprinkling of silver among his coa.r.s.e, intensely black hair, which he wore quite long, and also in his huge mustache and beard. His face was bronzed from exposure; there were crow's feet about his eyes, and two deep wrinkles between his brows, and his general appearance indicated that he had seen a good deal of the rough side of life.

He wore a coa.r.s.e though substantial suit of clothes, which hung rather loosely upon him; a gray flannel shirt with a turn-over collar, which was fastened at the throat by a flashy necktie, rather carelessly knotted; a red cotton handkerchief was just visible in one of his pockets; there were coa.r.s.e, clumsy boots on his feet, and he wore a wide-brimmed, slouch hat.

He inquired of the clerk, who came forward to wait upon him, if he could see the "boss of the consarn," as he had a little private business to transact with him.