At this moment Vitriol Bob reached the bottom of the stairs, when the Doctor sprang upon him with the sudden violence of a savage monster; and the murderer was thrown back on the steps.

“Treachery!” he exclaimed, in a tone resembling the subdued roar of a wild beast irritated by its keeper; and the two men were locked in a close embrace—a deadly struggle immediately commencing.

A mortal terror struck to the heart of Mrs. Mortimer, who knew full well that if her confederate should succumb, her own life would not be worth a moment’s purchase; and for upwards of a minute she stood rivetted to the spot, listening to the sounds of the conflict which she could not see.

Suddenly it struck her that she might aid her companion; and, taking from beneath her shawl a coil of rope with which she had intended to bind Torrens, whom she had made certain of subduing, she rushed to the scene of the struggle.

The gleam of light that reached that place, was sufficient, feeble though it were, to show her that Vitriol Bob had the advantage. He had succeeded in getting uppermost; and Jack Rily was struggling desperately underneath the man whose strength he had miscalculated. The conflict was thus progressing, accompanied by deep, low, but bitter execrations, when Mrs. Mortimer, whom a sense of danger suddenly restored to complete self-possession, threw a noose round Vitriol Bob’s neck, and instantly drew it tight,—exclaiming, as she performed this rapid and well-executed feat, “Courage, Rily,—courage: grasp him firmly—loosen not your hold!”

“Damnation!” ejaculated Vitriol Bob, the moment he felt the cord upon his neck and heard a strange female voice,—at the same time making a desperate—nay, almost superhuman effort to tear himself away from his foe and turn round on his new enemy.

But the woman drew the cord as tight as she could, and a sense of faintness came suddenly over the murderer,—so that Jack Rily was in another instant enabled to get uppermost once more.

“Tie his legs, old lady—and then we’ve nothing more to fear!” cried he, as he placed one knee on Vitriol Bob’s chest, and held the vanquished ruffian’s wrists firmly with the iron grasp of his sinewy hands. “Now, keep quiet, old fellow—or you’ll be strangled,” he continued, addressing himself to the wretch whose eyes glared savagely up at him even amidst the obscurity of the place: “It’s useless to resist—you are my prisoner,—and if it’s necessary to make you safer still, I’ll draw my clasp-knife across your throat—which I should be sorry to do, on account of old acquaintanceship.”

“What—what have I done to you—Jack—to—to deserve this?” gasped Vitriol Bob, half strangled with the noose, which, however, was now somewhat relaxed in consequence of Mrs. Mortimer being occupied in tying the other end of the rope round his ankles—a task which she performed with amazing skill and rapidity, and which, in consequence of Rily’s menaces, the vanquished one did not think it prudent to resist.

“I’ll tell you presently what you have done, Bob,” said the Doctor, in answer to the other’s query. “Now that you are bound neck and heels, you are not very formidable: nevertheless, I must just make your arms secure—and then we’ll hold a parley. Here, old lady—put your hand in the pocket on the right side of my coat, and give me out the cord you’ll find there. That’s right! Come—be steady, Bob—or I shall do you a mischief yet.”