doctor stephen follansbee walked along at a slow pace, but his movements were not characteristic. his hands were not folded behind him, and his head was erect, as if he were peering into the distance in front, instead of casting his eyes on the ground as he usually did.

he had walked down amsterdam avenue for several blocks when a faint monosyllable issued from his lips.

“ah!” he murmured, and sightly quickened his pace.

the young man who was keeping him in sight from the other side of the street—and who was evidently the same one who had opened the limousine door some time earlier—could not hear the ejaculation, but he noted the quickened steps and glanced ahead in search of a reason.

half a block beyond was a little group of men gathered on the sidewalk. when follansbee approached, he found that it consisted of a couple of policemen, and the driver of a taxicab was bending over the figure of a tall man lying prone on the sidewalk. the physician had no need to do more than glance at the figure, for, as the policeman lifted the body, the rigid features of james stone were revealed.

clearing his throat, follansbee stepped forward. “what’s the trouble, officer?” he asked. “has there been any accident?”

one of the men in uniform turned and looked at follansbee in a questioning way.

“i’m doctor stephen follansbee, of st. swithin’s hospital,” the specialist went on. “here’s my card. if i can help you in any way, i shall be only too glad to do so.”

the patrolman took the card and glanced at it in the light of a near-by street lamp. when he saw the name and the string of letters after it, his attitude instantly changed to one of great respect. it was a name to conjure with in new york city.

“it’s lucky you happened along, doctor follansbee,” the spokesman declared, making way for the newcomer, who stooped and seemed to make an examination.

“it seems to be a paralytic stroke,” follansbee announced presently. “you had better call an ambulance and have him taken somewhere at once.” then, as if struck by a new idea, he went on: “come to think of it, you might as well send him to st. swithin’s. i was going there in a few minutes, anyway. there’s a special case that needs watching. why not put him in this taxi?”

the cool cunning of the man had its reward.

under ordinary circumstances, the unfortunate stone would have been taken to another hospital—one with an emergency ward—but at follansbee’s suggestion the inert, heavily-breathing form was lifted into the machine, and one of the policeman took his place beside it. up amsterdam avenue, toward the big hospital over which follansbee presided, the cab made its way. follansbee himself had climbed into the seat beside the driver, and the ragged young man who had been following him looked uncertainly after the dwindling vehicle.

from that the vagrant’s gaze shifted to the remaining policeman, who was eying him suspiciously.

“this is no place for me,” thought the young fellow; and he made off hurriedly along the side street before the officer had time to accost him.

it was patsy garvan, nick carter’s second assistant, and he was doing an almost unheard-of thing. in other words, he was there without his chief’s knowledge or sanction. it was not as much of a breach of discipline as it might have been, however, for he was under chick’s orders. chick had something of a grudge against doctor follansbee, and had not been altogether satisfied with his chief’s assurance that he should have a hand in the case later on. it was impossible for him to do anything himself, because he was in charge at the detective’s headquarters in the absence of carter; but he had done the next best thing. he had found no trouble in inducing patsy garvan to shadow follansbee’s house while nick carter was watching james stone at the hotel.

“follansbee is a slippery customer,” chick had confided to the other, “and it strikes me that he needs a little attention. he’s capable of almost anything, and i’d like nothing better than to bring him up short without the chief’s help. as that’s out of the question, though, i’m going to turn him over to you. don’t let the chief know what you’re up to, if you can help it. i’d like to surprise him with some information that would be news to him; and when it comes to a showdown, i’ll take all the responsibility.”

patsy had accepted the added task with his usual promptness, and had been leading a sort of double life for several days. during the hours of daylight he went about his regular duties as usual. as it happened, nick did not give him much night work; consequently he was able to shadow follansbee’s house night after night. he had enjoyed little sleep, but he did not seem to mind that. he, too, was convinced that follansbee was an unusually dangerous man, and should be carefully “covered,” and he was more than willing to do the job.

now his feelings were decidedly mixed. he had ventured to mingle with the group about the prostrate man, and had discovered his identity. it was unquestionably james stone, the man he had seen entering follansbee’s house a short time before, and had subsequently left it.

patsy had seen follansbee watching stone as the latter started down the street, and he knew that the doctor had deliberately waited a few minutes, and then followed. this meant that the scoundrelly head of st. swithin’s had looked for stone to succumb on the street, and had planned to have it appear as if by accident.

“this is a queer go,” thought patsy as he hurried away from the neighborhood of the curious policeman. “follansbee must have double crossed stone just as patsy feared he might, and it was pretty foxy of him to have arranged that the man should take a tumble on the street several blocks from his house.

“i’ve stumbled over a discovery sure enough, and now it’s up to me to report to chick and let him tell the chief, as i suppose he will. it might have been well for me to trail that taxi in order to make sure of its destination, but i don’t believe there can be any doubt about that. follansbee suggested st. swithin’s, and the policeman who went along would want to know the why and wherefore of any change in plan. it seems safe enough to assume, therefore, that the buzzard is taking his latest victim to st. swithin’s, and that’s enough for the present. i’d like to know what the mischief he’s up to, and what he expects to do with him at the hospital, but that will have to keep. thank fortune i was on hand to-night. i’ll bet the chief didn’t dream that this little affair was going to be pulled off; if not, he certainly ought to thank chick and me for giving him the tip.”