the sudden command had been fully justified.

one of follansbee’s long, lean hands crept to his side—the side away from the detective—and had been extended toward an open drawer in the desk.

nick did not wait to see whether his order met with obedience or not. the words were still on his lips when he leaped to his feet and flung himself across the intervening space, grasping the thin, steel-like wrists of the physician.

the grip brought follansbee to his feet, and for a moment the two faced each other, their eyes flashing. perhaps the powerful grip of the detective’s fingers had warned follansbee of the uselessness of a struggle, but the unmasked, flaming rage in his face revealed the depth of his hatred.

a quiet smile flitted over the detective’s features. he quietly brought follansbee’s two wrists together, clasped them both with the fingers of one hand, and then leaning down, pulled out the open drawer a little farther.

as he had anticipated, he found a revolver in it. this he confiscated and dropped it into his pocket.

“i’ll take charge of this,” he announced. “all the same, though, i don’t trust you, and i must ask you to keep your hands on the desk hereafter. if you don’t, you may get hurt.”

with that he released follansbee and stepped back. the head of st. swithin’s glared at him for a few brief moments, then subsided into his chair again, and, with a sullen, venomous look, leaned both arms on the desk.

“i suppose there’s no use in playing the part any longer,” he confessed.

nick pricked up his ears at this and wondered if it were possible that follansbee was about to make a clean breast of it. the latter’s next words, however, proved that the hope was groundless.

“i was at the windermere last night,” follansbee declared coolly, “but not for the reason you think. james stone is my patient, and that’s why i consented to go through with that rather questionable farce. i can hardly blame you for misinterpreting it, but the fact remains——”

“drop it!” nick broke in. “i can guess what you’re going to say. you’re going to tell me that you were merely ‘humoring’ stone in an attempt to draw him out and get to the root of his disease. i suppose you think i’m green enough to believe that there was nothing harmful in that syringe.”

“nothing worse than glycerine,” the physician assured him.

nick’s laugh was harsh.

“you’re a fool, follansbee,” he declared. “you think you’re so clever that you can’t make yourself believe the other fellow has any brains at all.”

“do you think a man of my standing would deliberately lie?”

the detective might have said that he knew follansbee was lying, but he did not choose to do so for the very good reason that he did not wish the doctor to learn just then what he had done.

“standing hasn’t anything to do with it,” he answered. “it’s your personality i don’t trust, follansbee.”

the physician’s lips curled cynically. “that’s my misfortune—or yours,” he said. “you played the spy last night and heard some things which could easily be twisted. your interpretation is wide of the mark, however, and even if it were not, more than one witness would be required to give any weight to the evidence. you couldn’t prove anything against me if you tried, and i’m sure you’re too sensible to try. i have no personal knowledge of the matter, but i’ll wager that your friend is perfectly well and sound to-day. if he isn’t, it’s no fault of mine.”

“what’s the good of this fencing?” demanded the detective. “of course crawford is all right—so far as you know. that’s understood, and was provided for in your instructions to your tool. the stuff isn’t supposed to act at once, and that’s why you chose it. we’ll come back to that later on. what i want to make clear now is that i know exactly what you’ve done and that i also know you have already realized on your crime.”

doctor follansbee stiffened a little. “realized on my crime?” he cried. “what do you mean by that?”

“precisely what i say,” nick answered coolly. “i happened to make a call early this afternoon at a certain bank not far from the hotel windermere, and i had a very interesting interview with its cashier. he showed me three decidedly noteworthy documents—a note from you, one from james stone, and last, but not least, a check signed by stone, but otherwise filled in by you. it called for a huge amount, and had been cashed just before the bank closed.”

follansbee’s control was amazing.

“well, what of it?” he snarled. “everything was regular, wasn’t it? surely you haven’t any doubt of the genuineness of stone’s note? as for the check, it was for a large sum, i’ll admit, but every one knows that i exact large fees, and if a patient chooses to consider my services worth that much, it’s none of your business.”

“isn’t it? i’m afraid you’re mistaken there, follansbee. picture to yourself what it will mean when this thing comes out; when the world learns that you have obtained nearly half a million dollars by swindling a patient who trusted himself to you, and whose unsound mind made him an easy victim. how long do you think you will hold your position at the head of st. swithin’s? and how many of your rich patients will employ you again when it is known that you used disappearing ink to gain your unscrupulous ends? ah, i see that gets under your skin!”

the detective paused for a moment and watched the discomfited rascal through narrowed lids.

“i thought at first that stone had merely signed the check in blank,” he continued, “which would have implied a greater mental lack on his part and a lesser degree of criminality on yours; but now i know better. i took that check home with me, follansbee, and examined it under a microscope. thanks to that, i discovered that there had been other writing on it—doubtless in stone’s hand. your trick ink had quite disappeared, but the point of the pen had slightly scratched the surface of the paper; and, moreover, the application of a chemical on one or two spots revealed traces of the ink originally used. as soon as the bank gives me permission to do so, i shall apply that chemical—you can doubtless guess what it is—to the whole check, and thereby bring out the original writing once more. and when i do so, i’m sure i shall find that, as stone made it out, the check originally called for a much smaller sum. doubtless you found some excuse to change inks when it came to the signature, with the result that it alone was written with ordinary ink. what do you say to that?”

apparently follansbee had nothing to say. his hands were clenched on his desk and he was biting his under lip and glaring fearfully at the detective. nick returned look for look and allowed his glance to play over the surface of the desk. as it did so, it fell upon a letter which follansbee had been writing before his visitor’s entrance. the doctor’s name and address were engraved in the upper left-hand corner, and the ink in which the beginning of the letter was written was of the same shade as that used on the three documents which the detective had obtained at the bank.

“that reminds me,” said nick, looking from the unfinished letter to the open ink bottle.

he paused, and then with a swift movement thrust his hand out, picked up the bottle, corked it, and started to drop it into his pocket.

“this will be one more link in the chain—your chain,” he announced.

snarling like a wild beast, and with an agility for which nick had not given him credit, follansbee shot out of his chair and hurled himself upon the detective.

in the brief tussle which followed, the tables were turned, despite the detective’s greater bulk and strength.