At six-thirty that morning Margaret Halley was aroused by her maid—the latter but half awake—and sitting up in bed and switching on the lamp, she looked at the card which the servant had brought to her, and read the following:  
    CHIEF INSPECTOR KERRY,
    C.I.D.
    New Scotland Yard, S.W.I.
 
“Oh, dear,” she said sleepily, “what an appallingly early visitor. Is the bath ready yet, Janet?”
 
“I'm afraid not,” replied the maid, a plain, elderly woman of the old-fashioned useful servant type. “Shall I take a kettle into the bathroom?”
 
“Yes—that will have to do. Tell Inspector Kerry that I shall not be long.”
 
Five minutes later Margaret entered her little consulting-room, where Kerry, having adjusted his tie, was standing before the mirror in the overmantle, staring at a large photograph of the charming lady doctor in military uniform. Kerry's fierce eyes sparkled appreciatively as his glance rested on the tall figure arrayed in a woollen dressing-gown, the masculine style of which by no means disguised the beauty of Margaret's athletic figure. She had hastily arranged her bright hair with deliberate neglect of all affectation. She belonged to that ultra-modern school which scorns to sue masculine admiration, but which cannot dispense with it nevertheless. She aspired to be assessed upon an intellectual basis, an ambition which her unfortunate good looks rendered difficult of achievement.
 
“Good morning, Inspector,” she said composedly. “I was expecting you.”
 
“Really, miss?” Kerry stared curiously. “Then you know what I've come about?”
 
“I think so. Won't you sit down? I am afraid the room is rather cold. Is it about—Sir Lucien Pyne?”
 
“Well,” replied Kerry, “it concerns him certainly. I've been in communication by telephone with Hinkes, Mr. Monte Irvin's butler, and from him I learned that you were professionally attending Mrs. Irvin.”
 
“I was not her regular medical adviser, but—”
 
Margaret hesitated, glancing rapidly at the Inspector, and then down at the writing-table before which she was seated. She began to tap the blotting-pad with an ivory paper-knife. Kerry was watching her intently.
 
“Upon your evidence, Miss Halley,” he said rapidly, “may depend the life of the missing woman.”
 
“Oh!” cried Margaret, “whatever can have happened to her? I rang up as late as two o'clock this morning; after that I abandoned hope.”
 
“There's something underlying the case that I don't understand, miss. I look to you to put me wise.”
 
She turned to him impulsively.
 
“I will tell you all I know, Inspector,” she said. “I will be perfectly frank with you.”
 
“Good!” rapped Kerry. “Now—you have known Mrs. Monte Irvin for some time?”
 
“For about two years.”
 
“You didn't know her when she was on the stage?”
 
“No. I met her at a Red Cross concert at which she sang.”
 
“Do you think she loved her husband?”
 
“I know she did.”
 
“Was there any—prior attachment?”
 
“Not that I know of.”
 
“Mr. Quentin Gray?”
 
Margaret smiled, rather mirthlessly.
 
“He is my cousin, Inspector, and it was I who introduced him to Rita Irvin. I sincerely wish I had never done so. He lost his head completely.”
 
“There was nothing in Mrs. Irvin's attitude towards him to justify her husband's jealousy?”
 
“She was always frightfully indiscreet, Inspector, but nothing more. You see, she is greatly admired, and is used to the company of silly, adoring men. Her husband doesn't really understand the ways of these Bohemian folks. I knew it would lead to trouble sooner or later.”
 
“Ah!”
 
Chief Inspector Kerry thrust his hands into the pockets of his jacket.
 
“Now—Sir Lucien?”
 
Margaret tapped more rapidly with the paper-knife.
 
“Sir Lucien belonged to a set of which Rita had been a member during her stage career. I think—he admired her; in fact, I believe he had offered her marriage. But she did not care for him in the least—in that way.”
 
“Then in what way did she care for him?” rapped Kerry.
 
“Well—now we are coming to the point.” Momentarily she hesitated, then: “They were both addicted—”
 
“Yes?”
 
“—to drugs.”
 
“Eh?” Kerry's eyes grew hard and fierce in a moment. “What drugs?”
 
“All sorts of drugs. Shortly after I became acquainted with Rita Irvin I learned that she was a victim of the drug habit, and I tried to cure her. I regret to say that I failed. At that time she had acquired a taste for opium.”
 
Kerry said not a word, and Margaret raised her head and looked at him pathetically.
 
“I can see that you have no pity for the victims of this ghastly vice, Inspector Kerry,” she said.
 
“I haven't!” he snapped fiercely. “I admit I haven't, miss. It's bad enough in the heathens, but for an Englishwoman to dope herself is downright unchristian and beastly.”
 
“Yet I have come across so many of these cases, during the war and since, that I have begun to understand how easy, how dreadfully easy it is, for a woman especially, to fall into the fatal habit. Bereavement or that most frightful of all mental agonies, suspense, will too often lead the poor victim into the path that promises forgetfulness. Rita Irvin's case is less excusable. I think she must have begun drug-taking because of the mental and nervous exhaustion resulting from late hours and over-much gaiety. The demands of her profession proved too great for her impaired nervous energy, and she sought some stimulant which would enable her to appear bright on the stage when actually she should have been recuperating, in sleep, that loss of vital force which can be recuperated in no other way.”
 
“But opium!” snapped Kerry.
 
“I am afraid her other drug habits had impaired her will, and shaken her self-control. She was tempted to try opium by its promise of a new and novel excitement.”
 
“Her husband, I take it, was ignorant of all this?”
 
“I believe he was. Quentin—Mr. Gray—had no idea of it either.”
 
“Then it was Sir Lucien Pyne who was in her confidence in the matter?”
 
Margaret nodded slowly, still tapping the blotting-pad.
 
“He used to accompany her to places where drugs could be obtained, and on several occasions—I cannot say how many—I believe he went with her to some den in Chinatown. It may have been due to Mr. Irvin's discovery that his wife could not satisfactorily account for some of these absences from home which led him to suspect her fidelity.”
 
“Ah!” said Kerry hardly, “I shouldn't wonder. And now”—he thrust out a pointing finger—“where did she get these drugs?”
 
Margaret met the fierce stare composedly.
 
“I have said that I shall be quite frank,” she replied. “In my opinion she obtained them from Kazmah.”
 
“Kazmah!” shouted Kerry. “Excuse me, miss, but I see I've been wearing blinkers without knowing it! Kazmah's was a dope-shop?”
 
“That has been my belief for a long time, Inspector. I may add that I have never been able to obtain a shred of evidence to prove it. I am so keenly interested in seeing the people who pander to this horrible vice unmasked and dealt with as they merit, that I have tried many times to find out if my suspicion was correct.”
 
Inspector Kerry was writhing his shoulders excitedly. “Did you ever visit Kazmah?” he asked.
 
“Yes. I asked Rita Irvin to take me, but she refused, and I could see that the request embarrassed her. So I went alone.”
 
“Describe exactly what took place.”
 
Margaret Halley stared reflectively at the blotting-pad for a moment, and then described a typical seance at Kazmah's. In conclusion:
 
“As I came away,&r............