“Oh! is that so?” cried Cervera, as if amused.

“Very much so, senora.”

“And who does me the honor, pray?”

“I want you,” said Nick, bluntly.

“You, Detective Carter!  Why, sir, what an idea!  I wouldn’t have believed it of you.”

“Yet it is true, nevertheless.”

“Well, well,” repeated Cervera, with a pretty shrug, “I am really glad to hear you say so.  For what do you want me, Detective Carter?”

Not once had Nick’s searching gaze left her brazen countenance, and despite her outward display of badinage, his steadfast and penetrating eyes were making her secretly uneasy.

“I want you,” said Nick, pointedly, “for that ugly ‘Jack-in-the-box’ trick which you perpetrated this afternoon.”

Cervera’s eyes emitted a single swift, fiery gleam, and her red lips drew closer.  Yet she cried, still pleasantly: 

“What do you mean by that, Detective Carter?  Is it a joke?”

“You’ll find it no joke.”

“If it is, sir, I don’t see the point.”

“You will have a chance to look for it at the Tombs,” replied Nick, with grim quietude.  “Senora Cervera, I want you to go along with me.”

“The Tombs!  Go with you!  What do you mean?”

“I mean that you are now under arrest.”

“Arrest!  For what?”

“For the murder of a girl named Mary Barton,” Nick bluntly rejoined, ignoring the woman’s increasing display of amazement and resentment.

“Mary Barton!” cried Cervera.  “I never heard of the girl.”

“Nevertheless,” said Nick, sternly, “you met her on Fifth Avenue this afternoon, and gave her a jewel casket containing a venomous snake, which you had stolen from the den of Pandu Singe, and by which means you inadvertently killed Mary Barton, instead of another for whom your infernal design was intended.  I am aware of all of your late movements, senora, you see.”

“I see that you are a devil!” cried Cervera, with a sudden passionate outburst.  “How dare you come here with such a story as that?”

For a moment at least, the fact that Nick already had discovered nearly every detail of her infamous crime—­though committed only a few hours before—­almost completely unnerved her, and her changing countenance, her irrepressible outbreak, and the violent agitation of her lithe, nervous figure, were tokens of self-betrayal by no means unobserved by Nick.

“You’ll have a chance to refute the story before a judge and jury,” Nick curtly answered.  “At present you are in my custody, however, and you must go with me.”

Cervera rose to her feet, trembling visibly, and gripped the back of her chair as if for support.

“There must be some terrible mistake, Detective Carter,” she now cried, with well-feigned distress and alarm.  “Surely you do not mean this, sir?  Surely you do but jest?”

“On the contrary, senora, I mean every word that I have said.”