But before she was well in, her countenance changed.

"No," said she, "I want to think first. Give me time to think. I dare not say a word without thinking."

"Truth needs no consideration. If you wish to denounce this man——"

Her look said she did.

"Then now is the time."

She gave him a sharp glance; the first she had bestowed upon him since leaving Miss Althorpe's.

"You are no doctor," she declared. "Are you a police-officer?"

"I am a detective."

"Oh!" and she hesitated for a moment, shrinking from him with very natural distrust and aversion. "I have been in the toils then without knowing it; no wonder I am caught. But I am no criminal, sir; and if you are the one most in authority here, I beg the privilege of a few words with you before I am put into confinement."

"I will take you before the Superintendent," said Mr. Gryce. "But do you wish to go alone? Shall not Mr. Van Burnam accompany you?"

"Mr. Van Burnam?"

"Is it not he you wish to denounce?"

"I do not wish to denounce any one to-day."

"What do you wish?" asked Mr. Gryce.

"Let me see the man who has power to hold me here or let me go, and I will tell him."

"Very well," said Mr. Gryce, and led her into the presence of the Superintendent.

She was at this moment quite a different person from what she had been in the carriage. All that was girlish in her aspect or appealing in her bearing had faded away, evidently forever, and left in its place something at once so desperate and so deadly, that she seemed not only a woman but one of a very determined and dangerous nature. Her manner, however, was quiet, and it was only in her eye that one could see how near she was to frenzy.

She spoke before the Superintendent could address her.

"Sir," said she, "I have been brought here on account of a fearful crime I was unhappy enough to witness. I myself am innocent of that crime, but, so far as I know, there is no other person living save the guilty man who committed it, who can tell you how or why or by whom it was done. One man has been arrested for it and another has not. If you will give me two weeks of complete freedom, I will point out to you which is the veritable man of blood, and may Heaven have mercy on his soul!"

"She is mad," signified the Superintendent in by-play to Mr. Gryce.

But the latter shook his head; she was not mad yet.

"I know," she continued, without a hint of the timidity which seemed natural to her under other circumstances, "that this must seem a presumptuous request from one like me, but it is only by granting it that you will ever be able to lay your hand on the murderer of Mrs. Van Burnam. For I will never speak if I cannot speak in my own way and at my own time. The agonies I have suffered must have some compensation. Otherwise I should die of horror and my grief."

"And how do you hope to gain compensation by this delay?" expostulated the Superintendent. "Would you not meet with more satisfaction in denouncing him here and now before he can pass another night in fancied security?"

But she only repeated: "I have said two weeks, and two weeks I must have. Two weeks in which to come and go as I please. Two weeks!" And no argument they could advance succeeded in eliciting from her any other response or in altering in any way her air of quiet determination with its underlying suggestion of frenzy.

Acknowledging their mutual defeat by a look, the Superintendent and detective drew off to one side, and something like the following conversation took place between them.

"You think she's sane?"

"I do."

"And will remain so two weeks?"

"If humored."

"You are sure she is implicated in this crime?"

"She was a witness to it."

"And that she speaks the truth when she declares that she is the only person who can point out the criminal?"

"Yes; that is, she is the only one who will do it. The attitude taken by the Van Burnams, especially by Howard just now in the presence of this girl, shows how little we have to expect from them."

"Yet you think they know as much as she does about it?"

"I do not know what to think. For once I am baffled, Superintendent. Every passion which this woman possesses was roused by her unexpected meeting with Howard Van Burnam, and yet their indifference when confronted, as well as her present action, seems to argue a lack of connection between them which overthrows at once the theory of his guilt. Was it the sight of Franklin, then, which really affected her? and was her apparent indifference at meeting him only an evidence of her self-control? It seems an impossible conclusion to draw, and indeed there are nothing but hitches and improbable features in this case. Nothing fits; nothing jibes. I get just so far in it and then I run up against a wall. Either there is a superhuman power of duplicity in the persons who contrived this murder or we are on the wrong tack altogether."

"In other words, you have tried every means known to you to get at the truth of this matter, and failed."

"I have, sir; sorry as I may be to acknowledge it."

"Then we must accept her terms. She can be shadowed?"

"Every moment."

"Very well, then. Extreme cases must be met by extreme measures. We will let her have her swing, and see what comes of it. Revenge is a great weapon in the hands of a determined woman, and from her look I think she will make the most of it."

And returning to where the young girl stood, the Superintendent asked her whether she felt sure the murderer would not escape in the time that must elapse before his apprehension.

Instantly her cheek, which had looked as if it could never show color again, flushed a deep and painful scarlet, and she cried vehemently:

"If any hint of what is here passing should reach him I should be powerless to prevent his flight. Swear, then, that my very existence shall be kept a secret between you two, or I will do nothing towards his apprehension,—no, not even to save the innocent."

"We will not swear, but we will promise," returned the Superintendent. "And now, when may we expect to hear from you again?"

"Two weeks from to-night as the clock strikes eight. Be wherever I may chance to be at that hour, and see on whose arm I lay my hand. It will be that of the man who killed Mrs. Van Burnam."