once more nick carter eased himself out of his window. it was getting to be a habit with him. his long legs bridged the gap as before, but this time his errand was, if possible, even more fraught with risk than the previous ones had been.

he lowered himself over the rail slowly and with infinite care, and then, stooping, crept along the platform to stone’s window. by peering in through the crack between the sill and the partly lowered sash, he saw the tall miner in the act of picking up the little leather case from the writing desk. stone’s back was turned to the detective, and the latter seized the opportunity to slip noiselessly past the window.

a few feet ahead of him loomed another window, dark and open at top and bottom. winthrop crawford was fond of fresh air. the lower sash was raised about eighteen inches, which made it possible for nick to flatten himself over the sill and crawl through. it required daring under the circumstances, but his performance that night would have established a reputation for that sort of thing on the part of any one.

the room was in darkness, but the detective had previously found opportunity to study the position of the furniture. he was able, therefore, to avoid a collision, and his stockinged feet trod softly on the thick carpet. a private bathroom opened off from the bedroom on the side opposite the connecting door which led to stone’s quarters. nick darted into this and began cautiously to close the door.

“let’s hope our friend crawford is a sound sleeper,” he thought; “and that this door isn’t inclined to squeak. if he wakes up now and starts on a burglar hunt, it will mess things up hopelessly.”

crawford’s heavy breathing went on uninterruptedly, however, and the sound was reassuring. it seemed to indicate, on the other hand, that crawford would fall an easy victim to his old partner’s attack; but the detective had already pulled stone’s fangs.

he waited perhaps five minutes, standing behind the bathroom door, which he had left slightly ajar. at the end of that time the opposite door, that leading from stone’s room, quietly opened. as it did so, it revealed the fact that stone had put out his own lights. nick stiffened, for he knew that the crucial moment was close at hand.

he had taken the risk of entering crawford’s room and secreting himself there partly to witness whatever might happen, and partly because he was by no means sure of james stone. one never can be certain of what a madman may do. stone had been supplied with the instruments necessary for the commission of a highly scientific crime, but when the time came, he might discard them, owing to his unfamiliarity with such things, and resort to some more commonplace weapon. in fact, if he made a slip, or if crawford awoke prematurely and showed fight, it was almost certain that stone would try to make us of some more familiar way of getting rid of enemies—or supposed enemies. consequently nick wanted to be on hand to give instant aid, if necessary. he did not consider that his duty to crawford had been discharged when he had substituted water for the mysterious and deadly charge which doctor follansbee had originally placed in the hypodermic syringe.

stone came in noiselessly, and the subdued light from the corridor which shone in through the transom accentuated his lean, angular form as it entered. the door was closed carefully behind him, and nick could hear his suppressed, nervous breathing as he crossed toward the bed.

the intruder paused there within a yard or so of the outstretched form of crawford, and nick braced himself in anticipation of a possible emergency. he saw stone looking toward the bed with his head thrust slightly forward, as if he were listening to crawford’s breathing. seemingly the man soon became satisfied that all was well, for he took from his pocket a couple of small objects which the detective guessed to be the little vial and sponge.

stone’s movements indicated that he was emptying the contents of the vial into the sponge. as he did so, he took a quick step forward and bent over the bed. simultaneously there was a stir, and the springs of the bed creaked.

nick peered out and saw the head and shoulders of crawford rising from the pillow. the bearded face of the kindly mine owner peered for a moment through the gloom at the vague form bending over him, then a single word came to the detective’s ears:

“jimmy!”

a savage cry sounded, and, with a last bound, the demented partner had thrown himself upon crawford. nick heard a choking gasp, and for a moment was tempted to leap from his hiding place and hurl himself upon the would-be murderer. it was only with a supreme effort of will that he kept himself in hand and mutely watched the struggle.

stone had all the strength of his madness behind him, and with remorseless force he pressed crawford back upon the pillow. then, with a quick swoop, he pressed the sponge over the bearded lips and nostrils of the man who loved him better than a brother. there was a convulsive movement of the prone figure, and a long-drawn sigh, then crawford’s arms fell back from their hold on stone’s shoulders and he relapsed into unconsciousness.

stone’s heavy breathing was very audible to the detective as the latter stood watching the dramatic scene. he saw the miner take the little leather case from his pocket and remove the hypodermic syringe. after that, leaning over his unconscious partner, the madman plunged the needle into crawford’s forearm, close to the elbow, and the plunger was pressed home with one quick movement of the powerful thumb.

as soon as the deed was done, stone gave an exultant exclamation, and, still leaning over the bed, shook his clenched fists at the motionless body.

“it was either you or me, curse you!” he said, as if growling, his face working savagely. “and i have won. you’re as good as done for, and unless you stop playing with me as a cat plays with a mouse, you won’t have a chance to do what you want to do with me. i’ve taken care of myself so far, and i guess i can keep on doing it until you’re too sick to try any tricks on me. follansbee says you’ll be dead before the twenty-seventh, and he ought to know. anyway, he won’t get his money if you’re not.”