The taxi drew up to the curb. Billy Kane’s hat was far over his eyes as he stepped out. He stood an instant debating with himself, then handed the chauffeur another bill. What might happen at Jerry’s he did not know—he was going it blind again. But as a means of retreat, a taxi waiting around the corner would at least add to his chances, if necessity arose. And a chauffeur well paid was a guarantee of fidelity than which there was none better.

“You’ve struck a gold mine to-night,” he said coolly. “I may be gone half an hour, or I may be gone an hour—wait for me.”

“You bet your life, I’ll wait!” said the chauffeur fervently. “I——”

Billy Kane was hurrying down the street. He turned the first corner, and headed along the intersecting street, that was dark, narrow and deserted. He passed another cross street, and thereafter counted the houses as he went along. Here tenements and the old-fashioned dwellings of New York’s early days incongruously rubbed shoulders with one another. Jerry’s, he found, was the fifth house from the cross street. There was no mistaking Jerry’s. It was one of the old private dwellings, and it had been pointed out to him more than once. He returned to the cross street, turned down it, slipped into the lane that passed in the rear of the houses he had just inspected from the front, and, guardedly now, making his way silently along, he again counted the buildings that here in the darkness loomed up like black, uncouth shapes against the sky line. He stopped in the rear of the fifth house. Here and there a thread of light showed from a window, but it was a stealthy light, a light that played truant through the interstices of closed shutters, or seeped perhaps through the folds of curtains hanging inadvertently awry. It was abnormally dark, and in the darkness there seemed to lurk a somber secrecy, like a pall, cloaking evil things.

Billy Kane swung himself up and over a high fence, and dropped noiselessly to the ground on the other side. He found himself in a yard that, even in the darkness, he could make out was strangely restricted in area. A few feet in front of him was the wall of the building itself. He crept forward, skirting along this wall. There was no window, but opening almost on a level with the ground were shuttered French doors. He continued on, rounded the angle of the building, and suddenly stooped down in a crouching posture. There was a window here just above his head, and from it came a meager gleam of light. His eyes grown accustomed to the darkness, he could distinguish his surroundings a little more clearly now. The yard here, a narrow strip of it paralleling the side fence, seemed to run back quite a distance, taking up a jut in the building. They had puzzled him, those shuttered French doors where logically he had expected to find an ordinary back door and porch, but it was obvious now that the “back room at Jerry’s” was an addition that had been built onto the house, extending almost to the fence in the rear.

The window beneath which he crouched was shoulder high. He straightened up. The light came through slightly parted, heavy portiÈres. He felt the blood quicken suddenly in his veins. He could see in quite well. There were two men in the room—Karlin, and another man whom he did not recognize. The room was luxuriously, if somewhat garishly furnished. A green baize card table, with several unopened packs of cards upon it, stood in the center; there was a blue-and-gold Chinese rug with a huge dragon pattern upon the floor; and at one side a large buffet groaned under a load of wine and whisky bottles, bowls of fruit, and refreshments of various descriptions. The two men were talking earnestly. Karlin pulled out his watch, and scowled.

Billy Kane’s lips tightened. He could see, but he could not hear. He took his penknife from his pocket, and slipped the blade under the window sill. If he had luck, if the window was not locked, he—ah!—his breath came in a soft, long-drawn intake—the window gave slightly under a cautious pressure. An inch was all that was necessary, half an inch even. The window went up by infinitesimal fractions of that inch.

Billy Kane returned the penknife to his pocket. He could hear them now. Karlin was speaking; and the other man, it appeared now, was the proprietor of the place, Jerry, the ex-croupier of Monte Carlo.

“What’s the matter with you, Jerry—getting nervous waiting?” said Karlin curtly. “Well, forget it! This is the Rat’s plan—and that ought to be good enough, what? Nothing is going wrong, nothing can go wrong. Certainly, the police will close you up for a month, but that’s all there is to it, so far as you are concerned. They have nothing on you. That’s the inside of the whole thing—that the killing is done in an unpremeditated, drunken brawl over cards—that it just happened—just an untimely end without any other strings to it! There’s no reason why you should lose your nerve—your story is straight. Young Merxler came here often. He gives a little party here to-night. Neither you nor your doorkeeper knows a damned one of his guests. He vouched for them, and that’s all you know. You heard a row in here, then a revolver shot, and when you got here the table was upset, wine, cards and glasses all over the place, the boys beating it out through the French doors there, and young Merxler dead on the floor. You just notify the police. Your loss through being closed for a month makes it a cinch your story’s straight—you don’t have to tell the police that your share of the split is the best bet you ever made in your life! Let me do the worrying! I’m the one who’s taking the risk. I’m the one who’s been showing a seamy side to Merxler in confidence lately. I’m the one who’s invited him to the party that the police will be told he was giving. You can leave it to me that nothing goes wrong. I’ve got my own skin staked on this. There won’t be any mistake made—dead men can’t talk. The only thing I’m bothering about is what is keeping Bull McCann. He might——”

Billy Kane drew suddenly back from the window, and crouched down again against the wall of the building. Someone, unless he were curiously mistaken, was out there in the lane at the rear of the place. He was listening intently now—but there was a strange turmoil in his brain that seemed somehow to divide his attention, that had made his act of caution one that was almost purely automatic. Murder! That casual discussion of murder! There was something within him, soul deep, that he could not quite analyse—save that it seemed a lust for murder was upon him too, possessing him, engulfing him. Would that be murder? Was it murder to crush out the life of a poison-fanged snake! There was a fury upon him, but a most strange fury, a fury that was utterly cold—and utterly merciless. Murder! Yes, he knew now beyond question that there was to be murder, that the stage for it was set with a devil’s craft, with the craft of the Rat whose identity he had assumed; that it would appear on the face of it nothing more than quite a logical outcome of the life led by young Merxler, that there would appear to be no connection whatever with young Merxler’s death and what was to follow—but what was it that was to follow? How, in what way, was this murder, in dollars and cents, to show a profit at the next meeting of that unhallowed directorate of crime? How did Karlin——

Strange how his mind should isolate itself from his immediate surroundings, and yet leave him fully conscious of those surroundings! He was still listening—listening intently. There was no mistake. A boot scraped against a board. Someone was climbing the fence. Came then the soft thud of feet dropping to the ground, and now a quick step across the yard.

Billy Kane’s revolver was in his hand. If the newcomer came around the corner of the house, dark as it was, it was almost certain that—no! The other had halted evidently before those shuttered French doors, and was rapping softly—three raps, a single rap, two raps. The raps were repeated. Someone moved swiftly across the floor of the room. There was the faint clash of portiÈre rings, and the sound of the French doors being opened.

Billy Kane was at the window again. A third man was in the room now. Karlin was speaking sharply.

“You’ve been a long time coming, Bull!”

The newcomer, his back turned to Billy Kane, shrugged his shoulders.

“I had to wait until Merxler went out,” he answered. “I didn’t lose no time after that, an’ I came downtown as fast as I could. I ain’t been much more’n half an hour from Merxler’s to here.”

“Well, all right!” grunted Karlin. “Have any trouble?”

“Nix!” said the other. “I slipped the envelope into the drawer of the safe, all right. It was a cinch! The family was all upstairs.”

Karlin nodded.

“Where are the securities?” he demanded.

The man took what Billy Kane could see were a number of stock and bond certificates from his pocket, and handed them to Karlin.

Karlin nodded again, as he ran through the papers rapidly.

“How much did you leave in the safe?” he inquired crisply.

“What Red told me—about ten or twelve thousand.”

“All right!” said Karlin. “Good work, Bull! Beat it, now!”

The man turned, and left the room. Billy Kane heard him step across the yard, heard him climb the fence, heard Karlin within the room close the shuttered French doors—but this time Billy Kane made no movement, save that there was a curious twitching of his face muscles as his jaws locked together. All the bald, hellish brutality of the scheme was beginning to take form now in his mind. It was a plant, all of it, the letter, the will; a plant with the devil’s stamp of ingenuity upon it—and it was the man who had just gone from the room, Bull McCann, who had passed him on that black stairway from the basement in Merxler’s home!

Karlin was laughing in a viciously jubilant way, as he came back to the ex-croupier’s side.

“Fifty thousand dollars!” said Karlin, as he thrust the securities into the inside pocket of his coat, and patted the pocket complacently. “Fifty thousand, Jerry, and all of it in Theodore Rodger’s name—I kept stalling the kid on the idea of transferring the securities into his own name—told him there was no hurry—that he could clip the coupons and get the dividend checks through all right, just the same. I was his attorney too—see? Works pretty smooth, eh, Jerry? Too bad you didn’t get a chance to have a look at that letter and the will! The Chipper did the job, and they’re the best pieces of forged penwork that were ever pulled in America! Some head the Rat’s got, I’ll give him credit for that—he worded the letter. It’s prima facie evidence that the kid was blowing the coin just as fast as he did when he came into his father’s money—and nobody’s surprised that most of it has gone up in smoke. And, besides that, it’s a confession. Well, what happens? Merxler is killed in a gambling brawl—at which nobody is surprised, either!—his safe is opened, the will is found, and with it that little hymn of hate against me, which accounts for what would otherwise have been a fool play in having kept the will. I am found to be the executor, empowered to transfer and sell, and administer the estate—and we find that all that’s left is about ten thousand—which is all I have to account for. I enter that as the value of the estate, split it up among the beneficiaries, and”—he chuckled softly—“I generously waive my claim to any share in the legacy on the score that the estate has been so hard hit. Neat little play, eh, Jerry? Well, after that, there’s nothing to it! My signature is legally good on any document, and little by little, here and there, we turn the fifty thousand into the long green—and pocket it. If it’s done quietly, a security or so at a time, no one would ever think of digging around to find out if it was one of those on the schedule filed by the estate. Feeling better, Jerry?”

The ex-croupier walked over to the buffet, poured out for himself a stiff four fingers of whisky, and tossed off the neat spirit at a gulp. He forced an uneasy grin.

“I don’t often drink in business hours,” he said nervously. “But I’m not used to playing this high—maybe I’m a little shaky. Are you sure-fire on the witnesses to that will? Their signatures would have to be proved.”

“They’re the only things that are genuine,” said Karlin, with a malicious laugh. “We had two of our boys working around the hotel down on Long Island where Rodgers spent a month this spring, and where he is supposed to have written the will. They identify their signatures, and their story’s straight. Rodgers asked them to witness his signature to a paper, that’s all. He didn’t tell them what the paper was, and they didn’t know—see? If there’s any question crops up, the hotel proves that the two men were its employees at the time Rodgers was staying there.” He pulled out his watch again. “It’s ten o’clock!” he said brusquely. “Merxler ought to be showing up. I——”

The ex-croupier had suddenly laid a finger to his lips in caution. A knock was sounding on the hall door.

“Here he is now,” said the ex-croupier, in a lowered voice. “I told them to send him here as soon as he came.”

“All right, let him in,” instructed Karlin. “And tell the boys to drift along as soon as they like. It’s the man who cuts the first jack.”

The ex-croupier opened the door, and was instantly continental in both manner and speech. He bowed profoundly, as a young man entered.

“Ah, Monsieur Merxler—a great pleasure! I was telling Monsieur Karlin that——”

Billy Kane had drawn slightly back from the window. His lips were thinned, compressed. The fiendishness of it all had got him now—-Karlin with his suave, oily, Judas smile, preening at his Vandyke beard—and Merxler, for all that he had played the fool for several years now, still with a frank and boyish face, his broad shoulders squared back as he laughed a pleasant greeting. There was a whiteness in Billy Kane’s face, a whiteness that was like to the fury, no longer cold, that was white-hot in his soul. Murder! Well, perhaps—but it would not be Merxler’s murder! He whipped his mask from his pocket, and adjusted it swiftly over his face. His fingers automatically tested the mechanism of his revolver, as he again looked in through the window. The ex-croupier was bowing himself out of the room, closing the door behind him.

Quick and silent now in every movement, Billy Kane crept around the corner of the house, and crouched before the shuttered French doors. He had a minute, perhaps two at the outside, in which to act before Karlin’s confederates entered the room. He tapped softly with his revolver on the shutters—three raps, a single rap, two raps; he repeated it—three raps, a single rap, two raps.

From within a step came hurriedly across the floor, there was the faint clashing of the curtain rings again as the portiÈres were drawn aside, and through the interstices of the shutters came little gleams of light. Billy Kane shifted his grip upon his revolver—to the muzzle end. The doors opened a few inches cautiously. And then Karlin’s voice:

“Who’s there? What—-”

But Billy Kane was in action now, and the words ended in a wild shout of alarm. His left hand shot forward like a flash into the opening, wrenching the doors wide apart; and, lithe as a panther in its spring, he launched himself forward, and struck with the butt of his revolver, struck as he would have struck at a mad dog, full on Karlin’s head.

There was a crash as the man went limply, senseless, to the floor, and another cry, from Merxler now, and then, dazing Billy Kane for an instant by the sudden and unexpected onslaught, Merxler had sprung and locked his arms around him in a grip of steel. They crashed against the table, upsetting it.

“Let go!” Billy Kane panted frantically. “The hall door—lock it! You don’t understand!”

There was no answer from Merxler, save another hoarse shout for help. The boy was fighting like a demon. Here and there about the room they lurched, staggered, reeled, but Billy Kane was the stronger. It seemed only by inches, but still by inches they were nearing the hall door. There was something of ghastly irony in this frenzied effort of the boy to bar his own road to safety; but there was something fine in it too, something that, even as he fought, found recognition in Billy Kane’s mind. The boy, spendthrift though he might be, a fool with his money though he might be, was game to the core in standing by a man whom he believed to be his friend.

There was an uproar now from the interior of the house. There came the rush of feet along the hall. Another instant and they would be at the door. Massing his strength for the effort, Billy Kane tore himself free, flung Merxler back, and plunged forward. The door was being opened now. He hurled his weight against it.

“Quick, Merxler! Quick! The inside pocket of Karlin’s coat!” he gasped out. “Quick!”

There was a yell of fury from the hall, as the door slammed shut, and Billy Kane turned the key—and then a crash upon it, and another, as human battering rams launched themselves madly against the panels. Over his shoulder Billy Kane saw Merxler standing hesitant, glancing in stupefaction alternately from the door to Karlin on the floor.

A panel cracked and splintered. Billy Kane’s revolver roared like a cannon shot through the room. The bullet, aimed low, ripped along the threshold.

“Merxler, the inside pocket of Karlin’s coat!” he said in deadly quiet. “Man, are you mad! Hurry! They’ll have us both in another minute!”

The revolver shot had checked the rush against the door for an instant, though only for an instant, but that instant was enough. Merxler, stung into action, had leapt to Karlin’s side, and was bending over the man. And then he was on his feet, staring wildly at the papers in his hand.

“Good God, what’s this!” he cried out. “What’s——”

“The French doors—the fence—run for it!” said Billy Kane tensely, and fired again. And the next instant the room was in darkness, as he switched off the light; and in another, with Merxler running now beside him, he had crossed the few feet of yard and was swinging himself over the fence.

From behind came the rip and tear and smash of the yielding door, shouts, yells, oaths, a confusion of noises; but Billy Kane had reached the cross street now, and, pulling the mask from his face, jerking his hat brim far over his eyes, turned in the opposite direction from that in which he had entered the lane, and, urging Merxler on, was running at top speed. At the next block they swerved again—and Billy Kane, with a restraining pressure on Merxler’s arm, here dropped into a slower and less noticeable pace. There was little or no chance of pursuit now; no one, it seemed, had taken the immediate initiative of following them into the lane, yet Billy Kane made a wide detour before he finally reached his waiting taxi cab.

“Get in,” he said to Merxler; and, crisply, to the chauffeur: “Drive as fast as you know how! Go up the street at the rear of The Purple Scarf!”

He followed Merxler into the cab.

Merxler drew his hand across his eyes in a dazed way, and laughed nervously.

“I can’t see your face now, and you had a mask on before,” he said jerkily. “This is a queer business! Who are you? What’s it mean? Those securities were in my safe an hour ago—how did they get into Karlin’s pocket? What was he doing with them?”

“Stoop over!” said Billy Kane quietly. He handed Merxler the forged letter, and flashed the ray of his lamp upon the paper.

His head bent forward, Merxler read the letter, and his face, already white under the ray, gradually took on a drawn, grayish pallor.

“I—I never wrote this,” he faltered. “It’s my handwriting, but I—I never wrote it.”

“Nor your uncle this,” said Billy Kane, the same grim, quiet intonation in his voice, as he placed the will in turn in Merxler’s hand.

The light played on the paper, and over Merxler’s face. Billy Kane sat drawn back in the shadows.

There was moisture on Merxler’s forehead, as he looked up after a moment.

“My God,” he whispered hoarsely, “what does this mean?”

The flashlight was out. It was dark in the cab now, and the taxi rattled on traversing block after block. Billy Kane spoke swiftly, sketching the events of the night. Merxler did not move, save that at the end his hand sought and found and closed tight upon Billy Kane’s arm.

It was Merxler in a new light who spoke.

“You’ve saved my life—and you haven’t preached,” he said slowly. “I’m a fool! I’ve played the fool—they never would have tried to get away with it if I hadn’t played the fool all my life. I guess perhaps I’ve had my lesson tonight. But fool, or not”—his voice rasped suddenly, bitter hard—“Karlin will pay for this, or——”

“You will—yet!” Billy Kane cut in grimly. “You know too much, and you haven’t a minute to lose. They lost their heads for a moment in the confusion and the darkness when we got away, but their one hope now will be to get you before you tell your story. They may figure that you will hesitate about telling it, as you would have to admit your presence at Jerry’s gambling hell—and they may figure that you wouldn’t act anyway before morning. Do you understand? That’s their chance. Your chance is the police without a second’s delay—you may even get Karlin before he regains consciousness, or before they try to move him, if you’re quick enough. I know your story will sound strange with an unknown man in a mask running through it, but you have only to tell the truth. You have all the evidence you need. The police will know the Chipper, who forged the papers; and the police will know how to make those fake witnesses to the will squeal—it’s a different proposition now with them than simply appearing before Karlin and a notary public and swearing to the signatures. Understand?”

“Yes,” said Merxler tersely. “You’re right—and I’ll see it through. But you—you saved my life, and——”

“I get out here,” said Billy Kane, and leaning forward suddenly, tapped sharply on the glass front. They had turned into the street that was not only in the rear of The Purple Scarf, but was equally in the rear of that secret entrance into the Rat’s lair. He held out his hand to Merxler. “Good-night, Merxler—I——”

“But,” Merxler cried, as the taxi stopped, “I can’t let you go like this! I owe you too much. Who are you? What is your name? Where can I find you to——”

“I’m trying to find—myself,” said Billy Kane, with grim whimsicality. “Let it go at that!” He caught Merxler’s hand in a hard grip. “Good-night, Merxler—and good luck!” he said, and stepping quickly from the taxi, closed the door. He handed the chauffeur another bill. “Drive this gentleman to police headquarters—fast!” he ordered, and, turning, moved swiftly away down the street, hugging the shadows again, avoiding the rays of the street lamps.

He slipped into the lane, gained the shed, and from the shed made his way through the underground passage to the secret door, listened here intently for a moment, then stepped through into the Rat’s room, and groped forward toward the electric light that hung over the table.

It was strange! There was something almost mockingly ironic in it all! It was like the night before again. In peril himself as grave as Merxler’s, he had saved Merxler—and his own peril remained, was increased even, for the inner circle of this crime world that ranked him as a trusted confederate would be aroused now to an unbridled pitch of fury and excitement, seeking the unknown man in the mask who had foiled them to-night. Suspicious as they would be of every one, he now had that suspicion to combat, and he could ill afford that a breath of it should touch him. His all was at stake—Red Vallon, with the underworld at his heels, was enlisted now in a hunt for those rubies, which, if successful, must inevitably discover too the identity of the man, or men, who had murdered David Ellsworth, and who had driven him, Billy Kane, into this damnable exile! It was paramount, vital, that he should preserve his authority to keep the underworld at that work, the power to command, the——

Billy Kane switched on the electric light, and stood staring at the table, grim faced, his jaws locked tight together, his hand like a flash seeking his revolver in his pocket. His eyes lifted, and swept around the room. The swift, quick glance went unrewarded. The room was apparently as he had left it. He crossed quickly to the street door. It was still locked.

Again his eyes searched the room. He remembered that she had spoken of other secrets that the room possessed. What were they? Still another entrance? There was no sign of it! He knew only that someone had been here in his absence—and was now flaunting that visit in his face. Was it mockery? A warning? What?

It could not have been Red Vallon, or any of his pack. It was almost certain that Red Vallon had no knowledge of any secret entrance, and besides it was too soon for Red Vallon. Was it the woman? He shook his head. It was hardly likely, and his reason told him no—she had been outspoken enough that evening, and she had given no hint of this. Who then? And what was its meaning? Was it grim mockery? A grimmer warning? What?

On the table, ostentatiously placed in full view, and identified beyond possibility of mistake by a piece cut from the corner of the original plush tray on which it and many of its fellows had rested, was one of the rubies stolen from David Ellsworth’s vault!