For ten minutes the two heads of the detective service of London were in conference. Then there was an interruption. The door was pulled open without any preliminary knock, and Chief-Inspector Green strode swiftly in, with Robert Grell at his heels. Both men were plainly stirred by some suppressed excitement. Green laid a note down in front of Foyle.

"Petrovska has killed herself," he exclaimed. "The matron found her poisoned in her cell, a minute or so after I reached Malchester Row. There was poison in one of her rings. She left this letter addressed to you."

"Ah!" There was no betrayal of astonishment or any other emotion in the superintendent's tone. He fingered the letter carelessly. "Won't you sit down, Mr. Grell? No doubt you'll excuse us for a moment. Sit down, Green."

He tore open the letter and glanced over the neat, delicate handwriting. Thornton was leaning eagerly across the table. "A confession?" he asked.

"Yes—a confession," he replied. "Shall I read it aloud?" His eyes rested for an instant on Robert Grell. "You may care to hear it," he added.

"Go on," said Thornton.

Foyle spread the sheets on the table in front of him and began to read in a steady, expressionless tone.

"Heldon Foyle, Esq., Superintendent, C.I.D., New Scotland Yard, S.W.—Sir,—It would be futile, after what happened this morning, to dispute any longer the correctness of the conclusions you have come to. I killed Harry Goldenburg, and there is no need for any cant about repentance. He deserved all he got. As for myself, I was fool enough to step into a trap, and there is only one way out. I ought to have beaten you, but as I failed, it may interest you to know the bare facts.

"Goldenburg was, as you guessed, my husband, though it was long since we had lived together. Before I met him, however, I had become acquainted with Mr. Grell—I think it was in Vienna. I was on the stage there, and had a circle of admirers, of whom he became one. Whether you believe it or not, I assure you, on the word of a dying woman, there was nothing harmful in our intimacy. But letters passed, and his I kept.

"He disappeared out of my life after a while, and ultimately I met Goldenburg. We were both living on our wits. I, of course, could not fail to be struck by his astonishing likeness to Mr. Grell, and he told me eventually of their relationship. There is no use beating about the bush. Other people than Grell had written to me in the old days, and I had my own methods of forcing them to keep me silent. In plain words, a great part of my living was by blackmail, but I naturally acted very delicately. Harry Goldenburg wormed his way into my confidence, and it occurred to me that such a man would be an invaluable ally.

"We worked together for a while—I forgot to say we had been married—and I entrusted him with all the letters I had—including Grell's. Even the keenest woman will be a fool sometimes. You will guess what happened. He saw no need to share his plunder with me, and he left me. There was no open quarrel, but I determined that some day I would get even. But on the few occasions we met afterwards I preserved a friendly attitude. I even helped him in certain affairs.

"Then there came the time when Mr. Grell sought me out and paid me to attempt to recover his letters. I jumped at the chance, for apart from the money it seemed a fine opportunity to score off Goldenburg. I hadn't much difficulty in getting in touch with him when he reached London. He thought—and I encouraged the thought—that, like himself, I had been attracted here by the prospect of bleeding Grell on the eve of his marriage. I proposed a business partnership, and he, probably laughing in his sleeve, agreed. He had no intention of paying me my share, but he thought I might be useful in case the threat of publishing the letters might not be enough.

"But I never got the letters, although I used every means that occurred to me. I even suggested that he should entrust them to me so that I might try to extort money by their means from Lady Eileen Meredith. He would have none of it. I changed my ground and arranged to accompany him on what was to be the final decisive interview with Grell on his wedding eve.

"I said little during the preliminary talk. Both men were firm. Goldenburg declared that he would not give up the letters entirely. Grell was equally determined not to pay unless they were given to him.

"When I at length broke into the conversation I asked Grell for the letters I had written to him. I wanted to get him out of the room. He must have understood my look, for he at once said he had burnt them, but would make sure. He left the room. As soon as he was gone I played my final card with Goldenburg. I knew that the time had gone by for finesse; I told him that unless he gave up the letters I would suggest to Grell that he should declare them forgeries, and that I would bear him out.

"I think even Goldenburg was taken aback, for the revelation that I was playing double came as a shock to him. He laughed at me at first, but I could see that he had lost his temper. Then he swore at me for a Jezebel, and half rose as though he would strike me. But I was first. There was a dagger on the mantelpiece. For a moment I saw red. When I was again capable of thought I saw Goldenburg lying on the couch, motionless, and I knew what I had done.

"I struggled to get a grip on myself. At any moment Grell might return. I could not be sure of what he might do, and my whole idea was to save myself at any cost. Goldenburg had fallen back on the couch. I had taken two steps to the door when there was a sound outside. I drew back behind a curtain, expecting Grell. Instead of that a woman came in. She was heavily veiled, and though I did not know her then I was positive it was Lady Eileen Meredith, for Goldenburg had hinted at some such dramatic surprise if Grell did not come to terms. I saw her stoop over the murdered man, and then Grell opened the door. He stared for a second, and then closed the door again just as Lady Eileen looked up.

"To him it must have appeared that she had killed the man. I expected her to scream, but she did nothing of the sort. She went out, closing the door softly. I followed her within a minute or so, for I began to have an idea how things might be turned to my advantage. I went straight back to my hotel, and made arrangements to secure a sort of alibi. But I wanted to know how things were going. I had told Grell that if it became necessary to write me under cover, he might do so at the poste restante, Folkestone. There it was I heard before I returned to London. He declared that he had killed Goldenburg, a statement I had the best of reasons for knowing was false. But it left me with an easier mind. I had no wish that he should be questioned by the police, for that might have given rise to questions as to why I was at the house, and how I left.

"That was why I helped him by every means in my power. I think now it would have been perfectly easy for me to have disappeared without raising more than a fleeting suspicion in any one's mind. But we cannot foresee everything. And I believed that my safety lay in keeping Grell at liberty. What he thought of my motives for helping him, I do not know—he may have believed them to be gratitude, or something else. Anyway, he trusted me, and to make sure, I more than once hinted that I had an idea that Lady Eileen Meredith was the guilty person.

"It was I who supplied funds for the most part, and it was only when my resources threatened to give out, that we tried other methods. When I left for Liverpool, I was nearly at the bottom of my purse. The arrangement with Mr. Grell was, that I should remain in hiding there until such time as he could obtain money to enable us to get out of the country. Then I was to join him. I got a wire from him at last fixing Dalehurst Grange, and knowing that the stations would be watched, I determined to motor down.

"This explanation should make the things clear you do not already know,—L.P."

Heldon Foyle finished reading, and there was a moment's silence, broken at last by a gasp from Grell.

"It was she, then, not—not——"

"Not Lady Eileen Meredith," interrupted Foyle. "But do you confirm what she says there, Mr. Grell?"

Grell reached out, and took the paper with a hand that shook. He scanned it quickly, and handed it back to the superintendent.

"She is right in everything she says about me," he admitted. "I did think—God forgive me!—that my own eyes were right. I believed that Eileen had killed that man. That it was influenced me in everything I did. Till this moment, I had no idea——" He wheeled almost angrily on Green. "Why didn't you say why you brought me here?"

The chief inspector shrugged his shoulders. "My instructions were to bring you here—not to give explanations."

"I thought it best that you should learn all there was to know at your leisure," interjected Foyle. "Of course, we knew nothing of this"—he tapped the confession as he spoke—"before you came in."

Sir Hilary Thornton smoothed his moustache. "It has been an unpleasant business for all of us," he said urbanely, "and particularly for you, Mr. Grell. I can scarcely apologise for the trouble you have been caused, for, frankly, you have brought it all on yourself, though unofficially, I may say that I have never known a man behave with greater courage than you have in this matter. I am afraid that some of the things your fr——, your associates, have done, will have to be answered for, but anything consistent with our duty will be done for them. Perhaps Mr. Foyle will tell us the story of the case now. You are at least entitled to that."