dusk found stuart in a singular frame of mind. he was torn between duty—or what he conceived to be his duty—to the community, and … something else. a messenger from new scotland yard had brought him a bundle of documents relating to the case of sir frank narcombe, and a smaller packet touching upon the sudden end of henrik ericksen, the norwegian electrician, and the equally unexpected death of the grand duke ivan. there were medical certificates, proceedings of coroners, reports of detectives, evidence of specialists and statements of friends, relatives and servants of the deceased. a proper examination of all the documents represented many hours of close study.

stuart was flattered by the opinion held of his ability by the assistant commissioner, but dubious of his chance of detecting any flaw in the evidence which had escaped the scrutiny of so many highly trained observers.

he paced the study restlessly. although more than six hours had elapsed, he had not communicated to scotland yard the fact of his having seen mlle. dorian that afternoon. a hundred times he had read the message, although he knew it by heart, knew the form of every letter, the odd crossing of the _t'_s and the splashy dotting of the i's.

if only he could have taken counsel with someone—with someone not bound to act upon such information—it would have relieved his mental stress. his ideas were so chaotic that he felt himself to be incapable of approaching the task presented by the pile of papers lying upon his table.

the night was pleasantly warm and the sky cloudless. often enough he found himself glancing toward the opened french windows, and once he had peered closely across into the belt of shadow below the hedge, thinking that he had detected something which moved there. stepping to the window, the slinking shape had emerged into the moonlight—and had proclaimed itself to be that of a black cat!

yet he had been sorely tempted to act upon the advice so strangely offered. he refrained from doing so, however, reflecting that to spend his evenings with closed and barred shutters now that a spell of hot weather seemed to be imminent would be insufferable. up and down the room he paced tirelessly, always confronted by the eternal problem.

forcing himself at last to begin work if only as a sedative, he filled and lighted his pipe, turned off the centre lamp and lighted the reading lamp upon his table. he sat down to consider the papers bearing upon the death of eriksen. for half an hour he read on steadily and made a number of pencil notes. then he desisted and sat staring straight before him.

what possible motive could there be in assassinating these people? the case of the grand duke might be susceptible of explanation, but those of henrik ericksen and sir frank narcombe were not. furthermore he could perceive no links connecting the three, and no reason why they should have engaged the attention of a common enemy. such crimes would seem to be purposeless. assuming that "the scorpion" was an individual, that individual apparently was a dangerous homicidal maniac.

but, throughout the documents, he could discover no clue pointing to the existence of such an entity. "the scorpion" might be an invention of the fertile brain of m. gaston max; for it had become more and more evident, as he had read, that the attempt to trace these deaths to an identical source had originated at the service de surete, and it was from paris that the name "the scorpion" had come. the fate of max was significant, of course. the chances of his death proving to have been due to accident were almost negligible and the fact that a fragment of a golden scorpion had actually been found upon his body was certainly curious.

"close your shutters at night…."

how the words haunted him and how hotly he despised himself for a growing apprehension which refused to be ignored. it was more mental than physical, this dread which grew with the approach of midnight, and it resembled that which had robbed him of individuality and all but stricken him inert when he had seen upon the moon-bright screen of the curtains the shadow of a cowled man.

dark forces seemed to be stirring, and some unseen menace crept near to him out of the darkness.

the house was of early victorian fashion and massive folding shutters were provided to close the french windows. he never used them, as a matter of fact, but now he tested the fastenings which kept them in place against the inner wall and even moved them in order to learn if they were still serviceable.

of all the mysteries which baffled him, that of the piece of cardboard in the envelope sealed with a chinese coin was the most irritating. it seemed like the purposeless trick of a child, yet it had led to the presence of the cowled man—and to the presence of mlle. dorian. why?

he sat down at his table again.

"damn the whole business!" he said. "it is sending me crazy."

selecting from the heap of documents a large sheet of note-paper bearing a blue diagram of a human bust, marked with figures and marginal notes, he began to read the report to which it was appended—that of dr. halesowen. it stated that the late sir frank narcombe had a "horizontal" heart, slightly misplaced and dilatated, with other details which really threw no light whatever upon the cause of his death.

"i have a horizontal heart," growled stuart—"and considering my consumption of tobacco it is certainly dilatated. but i don't expect to drop dead in a theatre nevertheless."

he read on, striving to escape from that shadowy apprehension, but as he read he was listening to the night sounds of london, to the whirring of distant motors, the whistling of engines upon the railway and dim hooting of sirens from the thames. a slight breeze had arisen and it rustled in the feathery foliage of the acacias and made a whispering sound as it stirred the leaves of the privet hedge.

the drone of an approaching car reached his ears. pencil in hand, he sat listening. the sound grew louder, then ceased. either the car had passed or had stopped somewhere near the house. came a rap on the door.

"yes," called stuart and stood up, conscious of excitement.

mrs. m'gregor came in.

"there is nothing further you'll be wanting to-night?" she asked.

"no," said stuart, strangely disappointed, but smiling at the old lady cheerfully. "i shall turn in very shortly."

"a keen east wind has arisen," she continued, severely eyeing the opened windows, "and even for a medical man you are strangely imprudent. shall i shut the windows?"

"no, don't trouble, mrs. m'gregor. the room gets very stuffy with tobacco smoke, and really it is quite a warm night. i shall close them before i retire, of course."

"ah well," sighed mrs. m'gregor, preparing to depart. "good-night,

mr. keppel."

"good-night, mrs. m'gregor."

she retired, and stuart sat staring out into the darkness. he was not prone to superstition, but it seemed like tempting providence to remain there with the windows open any longer. yet paradoxically, he lacked the moral courage to close them—to admit to himself that he was afraid!

the telephone bell rang, and he started back in his chair as though to avoid a blow.

by doing so he avoided destruction.

at the very instant that the bell rang out sharply in the silence—so exact is the time-table of kismet—a needle-like ray of blue light shot across the lawn from beyond and above the hedge and—but for that nervous start—must have struck fully upon the back of stuart's skull. instead, it shone past his head, which it missed only by inches, and he experienced a sensation as though some one had buffeted him upon the cheek furiously. he pitched out of his chair and on to the carpet.

the first object which the ray touched was the telephone; and next, beyond it, a medical dictionary; beyond that again, the grate, in which a fire was laid.

"my god!" groaned stuart—"what is it!"

an intense crackling sound deafened him, and the air of the room seemed to have become hot as that of an oven. there came a series of dull reports—an uncanny wailing … and the needle-ray vanished. a monstrous shadow, moon-cast, which had lain across the carpet of the lawn—the shadow of a cowled man—vanished also.

clutching the side of his head, which throbbed and tingled as though from the blow of an open hand, stuart struggled to his feet. there was smoke in the room, a smell of burning and of fusing metal. he glared at the table madly.

the mouthpiece of the telephone had vanished!

"my god!" he groaned again, and clutched at the back of the chair.

his dictionary was smouldering slowly. it had a neat round hole some three inches in diameter, bored completely through, cover to cover! the fire in the grate was flaring up the chimney!

he heard the purr of a motor in the lane beside the house. the room was laden with suffocating fumes. stuart stood clutching the chair and striving to retain composure—sanity. the car moved out of the lane.

someone was running towards the back gate of the house … was scrambling over the hedge … was racing across the lawn!

a man burst into the study. he was a man of somewhat heavy build, clean-shaven and inclined to pallor. the hirsute blue tinge about his lips and jaw lent added vigour to a flexible but masterful mouth. his dark hair was tinged with grey, his dark eyes were brilliant with excitement. he was very smartly dressed and wore light tan gloves. he reeled suddenly, clutching at a chair for support.

"quick! quick!" he cried—"the telephone! … ah!"

just inside the window he stood, swaying and breathing rapidly, his gaze upon the instrument.

"mon dieu!" he cried—"what has happened, then!"

stuart stared at the new-comer dazedly.

"hell has been in my room!" he replied. "that's all!"

"ah!" said the stranger—"again he eludes me! the telephone was the only chance. pas d'blaque! we are finished!"

he dropped into a chair, removed his light grey hat and began to dry his moist brow with a fine silk handkerchief. stuart stared at him like a man who is stupefied. the room was still laden with strange fumes.

"blimey!" remarked the new-comer, and his whitechapel was as perfect as his montmatre. he was looking at the decapitated telephone. "this is a knock-out!"

"might i ask," said stuart, endeavouring to collect his scattered senses, "where you came from?"

"from up a tree!" was the astonishing reply. "it was the only way to get over!"

"up a tree!"

"exactly. yes, i was foolish. i am too heavy. but what could i do!

we must begin all over again."

stuart began to doubt his sanity. this was no ordinary man.

"might i ask," he said, "who you are and what you are doing in my house?"

"ah!" the stranger laughed merrily. "you wonder about me—i can see it. permit me to present myself—gaston max, at your service!"

"gaston max!" stuart glared at the speaker incredulously. "gaston max! why, i conduct a post mortem examination upon gaston max tomorrow, in order to learn if he was poisoned!"

"do not trouble, doctor. that poor fellow is not gaston max and he was not poisoned. you may accept my word for it. i had the misfortune to strangle him."