“The old fellow will think I’ve lost the trail when he finds he’s not followed,” he soliloquized, amid the joltings of the vehicle, “and maybe it will throw the hoodoo off the track.”

But Mr. Johnson had no intention of being thrown off.  He had seen cab No. 2 a take a different course, and, having lost sight of No. 1, decided that a bird in the hand would be worth two in the bush, and that he would follow up the “pal.”

As cab No. 2 approached Jefferson Street, Rosenbaum called to the driver to slacken and drive on the dark side of the alley.  He jumped out to reconnoitre; a cab was just stopping at No. 545, a tall figure got out and hastily disappeared up the steps, while the cab whirled rapidly away.

“Turn about, drive back quietly, and answer no questions,” Rosenbaum said, slipping a bill into the driver’s hand, and then glided swiftly through the shadow to No. 545.  His maneuvers were seen, however, by Mr. Johnson, who immediately proceeded to follow his example.

Running quickly up the steps to No. 545, Rosenbaum produced a bunch of skeleton keys, which he proceeded to try.  The first was useless, the second ditto; he heard steps approaching; the third fitted the lock, but, as it turned, a hand was laid upon his shoulder, a dark lantern flashed in his face, and a voice said,-

“Your game is up, my man; you had better come with me as peaceably as possible!”

For answer, the other turned quickly, and, without a word, lifted the lapel of his coat, where a star gleamed brightly in the rays of the lantern.

The band holding the lantern dropped suddenly, and its owner ejaculated, “Heavens and earth! what does this mean?  Who are you?”

“I am Dan McCabe, at your service,” was the cool reply; then, as the other remained speechless with astonishment, McCabe continued:  “I’ve no time to waste with you, Mr. Merrick; we may have a desperate piece of work on hand; but if you’ll come with me, I give you my word for it that before this job is over you’ll meet the biggest surprise of your life.”

Pushing open the door, McCabe noiselessly climbed the stairs, beckoning Merrick to follow.  By the light of the dark lantern he selected the door leading to the room occupied by Mannering, and, after listening a moment, nodded significantly to Merrick.

“Is he there?” the latter whispered.

“He is there,” said McCabe, grimly, “but not the man you are looking for.  I’ll tell you who is there,” and he whispered in his ear.

Merrick staggered as if from a blow.  “Great God!” he exclaimed aloud.

There was a sudden sound within as of some one frightened and moving hastily.  McCabe again called the man by name, and demanded admittance.  There was a moment’s silence, and then McCabe, with Merrick’s aid, forced in the door, and as it yielded there came from within the sharp report of a revolver, followed by a heavy groan.