shoot first and ask questions afterwards. It begins to look as if we had tracked the Whispering Thing to its lair. En avant!"
Cautiously and noiselessly, the two men made their way down the dark steps to the first floor. Followed closely by Bendlow, who had an automatic in his hand, Peret tip-toed across the hall and applied his ear to the keyhole in the front door. He heard a slight movement on the other side of the door, and his spine stiffened.
Peret waited, with his ear glued to the keyhole. He could plainly hear something moving around restlessly in the vestibule, but, for the moment, he could not determine what it was. Suddenly, however, he heard a thump on the door and a scratching sound on the floor. This was followed by a loud whining yawn.
Peret caught Bendlow by the arm and drew him away from the door.
"It's a dog," he whispered disgustedly. "Dalfonzo doubtless placed him there to guard the entrance during his absence. Lucky for us we entered by way of the cellar, eh?"
"I thought it might be a dog when I first hear it," muttered Bendlow; "but after what you said about the Whispering Thing I thought I better not investigate alone. Maybe the dog'll convince you that the Wolf is a tough customer. He's a hard man to catch napping. Going back upstairs?"
"No. I am through. There is no one in the house, and I can find no trace of the Whispering Thing. Sapristi! what a blind trail it is that I follow. Are you sure, my friend, that you have not made a mistake in thinking that Dalfonzo—"
"Not a chance," was Bendlow's emphatic reply. "This house, however, may be a blind. The Wolf may be laying low and working through his confederate. He may not even be in the city. However, as I am working in the dark, I will not hazard any more guesses. But you can bet your bottom dollar that the Wolf—"
"Hist!"
But Peret's warning came too late. Engrossed as they were in their whispered conversation, neither of them had heard the outer front door open, or the whine with which the dog welcomed the man who entered the vestibule. Peret's alert ear had caught the sound made by a key being turned in the lock of the inner door, and he hissed his warning just as the door was opened to admit the man and the dog. At the same instant a match flared in the hand of the new-comer, and the two detectives, as if on pivots, whirled.
"The Wolf," croaked Bendlow hoarsely, and, with Peret following darted down the hall.
"Halt!" commanded the Wolf, and the dog, with an angry growl, shot between his legs and hurled itself after the detectives.
Reaching the door at the head of the cellar steps, Bendlow grasped the knob and wrenched it open. A streak of flame stabbed the darkness and a bullet zummed by Peret's ear and buried itself in the wall.
"Get him, Sultan," cried the Wolf, and fired another shot.
Sultan tore down the dark hall, his lower jaw hung low in readiness, but when he reached the end of the hall he found the two prowlers had disappeared and the cellar door was closed.
CHAPTER VI.
THE WHISPERING THING.
IF SULTAN was doomed to disappointment, so, too, were Peret and his husky companion, for they were not to make their escape as easily as they had at first believed they would. As they climbed from the basement window a dark form loomed up in front of them and a harsh voice commanded
"Hands up!"
