Mona drew her purse from her pocket, found the precious piece of cloth that Ray had sent to her, and laid it over the hole in the skirt.

It fitted perfectly into the tear, and she knew that the dress which the beautiful Mrs. Vanderbeck had worn, when she stole the Palmer diamonds, was found.

But the woman!

Mona was puzzled, for surely the woman whom she had seen wearing the dress was much older than the one whom Ray had described to her.  She was wrinkled and gray; and then—­the name!  But stay!  All at once light broke in upon her.  Walton had been the name of the person who had so cleverly deceived Dr. Wesselhoff.  She had been old and wrinkled, and now, without doubt, she had come to St. Louis to dispose of her share of the stolen diamonds, and had worn the other woman’s dress, thinking, perhaps, it would be safe to do so, and would not be recognized under such different circumstances.

“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.