It did not take him long to decide upon his course of action, and he was now again the cool and collected detective, although the fierce glitter in his eyes betrayed some relentless purpose in his mind.

He made his way quietly into a corner, where he stood covertly watching the brilliant woman, and comparing her appearance with a description that was written in cipher upon some tablets which he took from his pocket.

“’Very attractive, about twenty-eight or thirty years, rather above medium height, somewhat inclined toward embonpoint, fair complexion, blue eyes, short, curling red hair,’—­Hum!” he softly interposed at this point, “she answers very well to all except the red hair; but drop a red wig over her light-colored pate, tint her eyebrows and lashes with the same color, and I’ll wager my badge against a last year’s hat we’d have the Bently widow complete.  There can be no doubt about the crescents, though, and that cross on her bosom looks wonderfully like the one that Palmer described to me.  I suppose she thought no one would be on the lookout for it here, and she could safely wear it with all the rest, I always said the same woman put up both jobs,” he interposed, with a satisfied chuckle.  “Guess I’ll take a nearer look at the stones, though, before I do anything desperate.”

He put up his tablets, and began to move slowly about the rooms; but his eagle eye never once left the form of the woman in white brocaded velvet.

Three hours later, Mrs. Vanderheck, wrapped in an elegant circular of crimson satin, bordered with ermine, and attended by her maid and a dignified policeman as a body-guard, swept down the grand stair-way leading from the ball-room to the street, on her way to her carriage.

As she stepped out across the pavement and was about to enter the vehicle, a quiet, gentlemanly looking person approached her and saluted her respectfully.

“Madame—­Mrs. Vander_beck_,” with an intentional emphasis on the last syllable, “you are my prisoner!”

The woman gave a violent start as she caught the name, and darted a keen glance of inquiry at him, all of which Mr. Rider was quick to note.

Then she drew herself up haughtily.

“Sir, I do not know you, and my name is not Vander_beck_; you have made a mistake,” she said, icily.

“I have made no mistake.  You are the woman I have been looking for, for more than three years, whether you spell your name with a b, an h, or in a different way altogether; and I repeat—­you are my prisoner.”

Mr. Rider laid his hand firmly but respectfully on her arm, as he ceased speaking, to enforce his meaning.

She shook him off impatiently.

“What is the meaning of this strange proceeding?” she demanded, indignantly; then turning to the policeman who attended her, she continued, in a voice of command:  “I appeal to you for protection against such insolence.”