The words were spoken aloud in a thick, jerky voice, and it seemed to be all that Stone could do to keep his clutching hands from his senseless partner’s throat. Doubtless he remembered the rascally doctor’s promise that Crawford would know nothing about it all when he woke in the morning, and that was probably what stayed his hand.  
 
Had the detective been in any doubt of the man’s condition, it would have vanished then, and Stone’s irresponsibility was even more evident when he turned away from the bed, and the light from the transom struck his face. It was wrinkled into a mask of maniacal triumph, and the glare in the eyes was more like that of a wild animal than of a human being.
 
Nick held his breath for a moment. Stone was heading directly toward the bathroom, apparently with the idea of washing his hands after handling the drugged sponge. If he should enter there, discovery would be inevitable, and the detective would have a crazy man to handle—a task which even he did not care to contemplate.
 
Presently, however, when Stone was only four or five feet from the door of the bathroom, he suddenly wheeled about and recrossed to his own door, through which he disappeared. His shrewdness had evidently suggested the desirability of performing the necessary ablutions in his own room.
 
Nick relaxed when the danger was removed, and after waiting for perhaps five minutes following the closing of the connecting door, he stole from his hiding place and sought Crawford’s bed. No odor of the drug had reached his nostrils in the bathroom. It was evidently so volatile that it had been quickly dissipated in the air. The detective knew its nature, however, for he had sniffed at it in Stone’s room. He was aware that it was all that Doctor Follansbee had claimed for it, and that, under ordinary circumstances, it would work no permanent harm; but what he did not know was its effect on Winthrop Crawford. Crawford seemed to possess a rugged constitution, but his heart, for instance, might be weak. Nick wished to make sure that his new friend’s condition was normal before he left the room.
 
His examination, for which he did not need a light, was satisfactory. The drug had plunged Crawford into a profound sleep, but there was nothing to indicate that the effects would not pass away in good time, leaving him in his usual health. As for the injection, that meant nothing, so long as the serum which Follansbee had provided was now reposing in Nick’s fountain pen. To be sure, the hasty cleaning of the syringe might not have removed all traces of the serum, but the detective had done his best, and knew enough of such things to feel sure that the consequences, if any, would not be serious. Crawford might possibly have a slight touch of the disease, whatever it was, but it was not likely to amount to much.
 
The detective straightened up a little, listened, then produced his pocket flash light and turned the rays on Crawford. It was an easy matter to find where the puncture had been made, for a tiny globule of blood stood out on the tanned skin of the............