Ten minutes later I was standing in a charming little boudoir which too often figured in my daydreams. My own photograph was upon the mantelpiece, and in Isobel's dark eyes when she greeted me there was a light which I lacked the courage to try to understand. I had not at that time learned what I learned later, and have already indicated, that my own foolish silence had wounded Isobel as deeply as her subsequent engagement to Eric Coverly had wounded me.  
The psychology of a woman is intriguing in its very naïveté, and now as she stood before me, slim and graceful in her well-cut walking costume, a quick flicker of red flaming in her cheeks and her eyes alight with that sweet tantalizing look in which expectation and a hot pride were mingled, I wondered and felt sick at heart. Desirable she was beyond any other woman I had known, and I called myself witling coward, to have avoided putting my fortune to the test on that fatal day of my departure for Mesopotamia. For just as she looked at me now she had looked at me then. But to-day she was evidently on the point of setting out—I did not doubt with the purpose of meeting Eric Coverly; on that day of the irrevocable past she had been free and I had been silent.
 
"You nearly missed me, Jack," she said gayly. "I was just going out."
 
By the very good-fellowship of her greeting she restored me to myself and enabled me to stamp down—at least temporarily—the monster through whose greedy eyes I had found myself considering the happiness of Eric Coverly.
 
"I am afraid, Isobel," I replied, "that what I have to tell you is not by any means pleasant—although—"
 
"Yes?" she prompted, noting how I hesitated.
 
"Although it means that you are now the future Lady Coverly."
 
The bright color left her cheeks. That some black tragedy underlay my words she had intuitively perceived, but I could see that she failed to grasp the whole meaning of my bald statement. She sank down slowly into a cushioned chair, so that a beam of golden light pouring in through the opened window set aglowing the russet tints in her dark brown hair.
 
"Did you know Sir Marcus?" I asked, speaking as gently as I could.
 
With what intense, if hidden, emotion I awaited her answer it were impossible to describe.
 
"Do you mean—"
 
She met my glance, and I nodded gravely.
 
"Oh, Jack! When did it happen?"
 
"Last night. But you have not told me if you knew him?" I persisted.
 
Isobel shook her head.
 
"Not in any way—intimately," she replied. "Eric"—she hesitated, glancing up quickly and as quickly down again—"and he were not on good terms."
 
"But you had met him?" I persisted; for I had detected in her manner a reluctance to discuss Sir Marcus which I failed to understand.
 
"I used to meet him, Jack, when—when you were away. He came once or twice with Eric. They were not good friends, even then. But I never liked him. I quite lost sight of him from the time that he came into the title—about four years ago, was it not?—until quite recently. He had been in Russia, I think. Then he—" Again she hesitated. It was odd how often people hesitated, as if seeking for words, when speaking of the late baronet. "He called at the theater. Considering that he knew of my engagement to Eric, his manner was not quite nice. But I was anxious to prevent trouble, and did not mention the visit to Eric. Sir Marcus was very persistent, however. One night Eric saw him leaving the stage-door and I believe there was a dreadful scene at Eric's rooms."
 
"And that is all you know of him, Isobel?"
 
"Practically all, except what I have heard, of course. I might add that I instructed Marie to tell Sir Marcus I was engaged whenever he might call in future."
 
"And did he call again?"
 
"Marie said that he sent his card up on several occasions, but she knew how the affair worried me and did not tell me at the time. I saw him in the stalls occasionally, and—oh!—"
 
The last word was a mere murmur. Isobel's expression grew more than ever troubled.
 
"He was there last night," she whispered, and raising her eyes to me: "Tell me how it happened, and where—"
 
But ere I had time to begin there was an interruption. Dimly, a telephone bell rang. I could hear the voice of Marie, Isobel's maid, answering the call then:
 
"Mr. Coverly to speak to you, madam," said Marie, entering the room.
 
"He must have only just heard the news!" cried Isobel, rising swiftly and going out.
 
Consumed by impatience, I walked up and down the dainty apartment listening to Isobel's muffled voice speaking in the lobby. Twice I went to the window and peered down into the street, expecting to see the thick-set figure of Inspector Gatton approaching. My frame of mind was peculiar and troubled. Gatton's inquiries pointed unmistakably to a suspicion that Sir Marcus's last hours had been spent, if not actually with, at any rate near to Isobel. And since the man who would most directly profit by the baronet's death happened also to be Isobel's fiancé, I foresaw a dreadful ordeal for both if Eric Coverly was not in a position to establish an alibi.
 
I had been about to ask her if Coverly had been in her company on the previous night when the interruption had occurred. Now if Gatton should arrive and find me in Isobel's flat, what construction would he put upon my presence?
 
Yet again I went to the window and peered anxiously up and down the street. Every cab that approached I expected to contain the inspector, and I heaved a sigh of relief as one after another passed the door. Pedestrians who turned the distant corner I scrutinized closely and was so employed when Isobel came running back to the room.
 
All her color had fled and her eyes were wide and fear-stricken.
 
"Oh, Jack, Jack!" she cried, "it is horrible, horrible! Eric is at his solicitors' and they tell him that suspicion is bound to fall on him! It's preposterous—unthinkable. It must have been some fiend who committed such a crime, not a human being—"
 
"Then," I interrupted excitedly, "Coverly was not with you last night?"
 
"No! That is the crowning tragedy of it all. He 'phoned me early in the evening saying that he had an unavoidable business appointment to keep. From the tone of his voice—"
 
She ceased speaking abruptly, and stared at me rather wildly.
 
"Isobel," I said, "you should surely know that you can trust your life to me—and the life of any one dear to you."
 
She quickly laid her hand on my arm and her face flushed sweetly. I fear I had infused my words with an ardor which exhibited at an earlier and more opportune moment might have changed the course of both our lives.
 
"Of course I know, Jack," she said. "But I am so frightened that I distrust my very self. Well, then, I thought that I noticed a change in Eric's manner last night—in the tone of his voice. In fact I asked him if I had done anything of which he had disapproved." She gave me a quick little embarrassed glance. "He is somewhat exacting, you know. He laughed at the idea, but in rather a forced way, it seemed. Then he arranged to meet me for lunch at the Carlton to-day."
 
"But surely he can satisfactorily account for his movements? He must have been seen by those who know him."
 
Isobel frowned in a troubled manner that awakened strange, wild longings.
 
"I cannot make it out," she replied. "He appears to be keeping something back."
 
"He is very ill-advised. He will certainly have to make up his mind to speak out when Inspector Gatton examines him. I cannot disguise from you, Isobel, that the police know that Sir Marcus was at the New Avenue last night, and since his death occurred some hours later the nature of their suspicion is obvious enough. Are you joining him at the solicitors', Isobel?"
 
"Yes, he asked me to do so."
 
"Then come along at once. I expect a Scotland Yard man to arrive at any moment and it would be advisable to see Coverly and to take a legal opinion before you give your testimony."
 
"But, Jack!" Isobel confronted me. "You don't think that I or Eric have anything to hide?"
 
"Certainly not. You must know that I do not think so. But on the other hand, the legal mind being used to considering problems of evidence, a solicitor will be able to advise you of the best course to adopt, and that most likely to result in your being spared all association with the inquiry. Meanwhile—let us hurry. I prefer to give Inspector Gatton my own account of this visit rather than to be discovered here by him. He will learn from Marie that I have called, of course, but that doesn't matter."
 
We had now quitted the flat and were descending the stairs. On reaching the street I glanced sharply to right and left. But Gatton was not in sight.
 
I secured a taxi at the corner and Isobel set out for the office of Coverly's solicitor. I stood looking after the cab until it was out of sight and then I set out to walk to the Planet office. By the time that I had reached Fleet Street I had my ideas in some sort of order and I sat down to write the first of my articles on the "Oritoga mystery"—for under that title the murder of Sir Marcus Coverly was destined to figure as the cause célèbre of the moment. I had more than one reason for reticence and indeed I experienced no little difficulty in preparing the requisite amount of copy without involving Isobel and Eric Coverly. Half-way through my task I paused, laid down my pen, and was on the point of tearing up the pages already written and declining the commission at the eleventh hour.
 
A few minutes' reflection, however, enabled me to see that the best service I could offer to the suspected man (always assuming that he had no alibi to offer) was that of representing the facts as I saw them to the vast public reached by this influential journal. In my own mind I had never entertained a shadow of suspicion that Coverly was the culprit. Underlying the horrible case I thought I could perceive even darker things—a mystery within a mystery; a horror overtopping horror.
 
I had just resumed work, then, when a boy came in to inform me that Gatton had rung up and wished to speak to me.
 
Half fearful of what I should hear, I went to the adjoining room and took up the receiver. Presently:
 
"Hullo! Is that Mr. Addison?" came Gatton's voice.
 
"Yes, speaking. What developments, Gatton?"
 
"Several. I've got the report of the estate-agent and I've seen the stage-doorkeeper of the New Avenue! You mustn't write anything until I see you, but in order to regularize things a bit I've spoken to the Chief and formally asked his permission to consult you on the case—about the Egyptian figures, you know. He remembered you at once, so it's all square. But I've got a bone to pick with you."
 
"What is that?"
 
"Never mind now. Can you meet me at the Red House at five o'clock?"
 
"Yes. I will be there."
 
"Good. I don't hope for much. It's the strangest case I ever touched. We are dealing with unusual people, not ordinary criminals."
 
"I agree."
 
"If there is any man in London who can see daylight through the mystery I believe you are the man. Do you know on what I think the whole thing turns?"
 
"On some undiscovered incident in Sir Marcus's past, beyond a doubt. Probably an amorous adventure."
 
"You're wrong," said Gatton grimly. "It turns on the figure of the green cat. Good-by. Five o'clock."