It was a large, square chamber, and elaborately furnished.  The two windows were well above the street, and offered no chance for escape.  There were but two doors, that leading into the hall and the one leading into a large closet in the opposite wall.

Nick opened the latter, and found the closet hung with Cervera’s extensive wardrobe.  He thrust his arm along the garments hanging at either side, and sounded the three walls, and then the closet floor, all of which appeared perfectly firm and solid.

Even these precautions seemed quite needless to Nick, however, it being a rented house, and Cervera presumably uninformed of his coming.

“Now, senora, you may have just ten minutes to make ready,” said he, as he rejoined her.  “I shall leave this chamber door open, and will wait for you in the adjoining hall.  Can you whistle?”

“Whistle?”

“Yes, whistle!  You know what it is to whistle, don’t you?”

The sneer on Cervera’s red lips, as she arose from her chair, became almost a smile.

“Yes, I can whistle after a fashion,” she admitted.

“Well, then, you keep whistling all the time you are alone here,” Nick sternly commanded.  “I will let you out of my sight to make these changes, but not out of my hearing.”

“Suspicious fool!”

“Fool or not, you keep whistling,” said Nick, bluntly.  “If you let up for so long as a second, I’ll come over yonder threshold in a way that you’ll not fancy.”

“But suppose I want to brush my teeth?” inquired Cervera, with a vixenish light in her evil eyes.  “I cannot whistle and brush my teeth, Detective Carter.”

“You’ll have plenty of time to brush your teeth at the Tombs,” said Nick, sharply.  “Now look lively, mark you, and—­keep whistling.”

Cervera at once began to whistle.

Nick removed the key from the chamber door, and sauntered out into the hall, where he kept his ears constantly alert.

Not for a moment did the whistling cease, nor was there the slightest change in tone or character.

Nick could not have taken a more effective method to serve his present purpose.

At the end of eight minutes the whistling ceased, and Cervera coldly cried: 

“Now you may come in, Detective Carter.  I am about ready to go with you.”

Mick at once entered the chamber.

Cervera had changed her evening dress for a complete suit of black, and was standing in the middle of the room.

“I suppose,” said she, staring icily at the detective, “that I ought to thank you for your consideration.”

“Don’t trouble yourself,” said Nick, curtly.  “I have no time to waste.”

“Yet just one word, Detective Carter, before we go.”

“Let it be brief, then.”

“You are said to be a very clever man, and no doubt you think you have me dead to rights in this case,” said Cervera, with a mocking curl of her thin lips.