Davis directed a keen glance at his elder sister over the bowed head of Iris. The younger woman was by no means of an emotional nature. Light, frivolous and volatile, she had danced through life, and, on the whole, had had a good time. One could not picture her in a tragic mood.

And yet, she was the personification of deep emotion now. She could hardly speak for those convulsive sobs, and in her frightened eyes there was a deep and haunting terror. At what point, and through what circumstances, had tragedy touched this little selfish, self-centred butterfly, gifted with a certain amount of cunning and sharpness, but utterly brainless.

"What do you know of No. 10 Cathcart Square, except what you gleaned from the newspapers?" demanded her brother sternly. "How can you be implicated in the murder of the unknown man whom Carrie mistook for me?"

"But Carrie did not mistake him for you," wailed Iris. "She told me afterwards that the idea suggested itself in a flash, and when she read the newspaper she was not sure whether it was you who had crept in there, according to the evidence, and made away with yourself, through fear of the police."

"Leave Carrie out of it for the moment," said Davis. "Whatever she did was well thought out. Of course, we both know her object was to identify me, if possible, and put Scotland Yard off the scent. What we want to know is, how did you come to be acquainted with the house? what do you mean by saying that, if further investigations are made, you might be dragged in?"

"I was there on four occasions: on the last a few days before the murder, or suicide, whatever it was."

Davis gasped, and Carrie lifted her hands in horror. What did this confession mean? It was impossible that this slim, weak girl had herself been the murderess, could have killed a big, powerful man of the same build as the supposed Davis, with those slim, weak hands.

She saw the horror in their faces, and hastened to reassure them. "Oh no, not that, I swear to you. I am no more a murderess than you were a murderer, Reggie. But if the whole thing is raked up, and the man whom I believe it to be, accurately identified this time, things might look very black for me."

Davis lifted her from her kneeling position, and placed her in an easy-chair. "Calm yourself, and tell us the whole story of why and how you came to be in Cathcart Square at all."

Iris waited a few moments till the convulsive sobbing ceased. She spoke with little occasional gasps, but it was very evident it was a relief to unbosom herself.

"It is a very long story," she began tremulously.

"If the telling of it lasts till midnight, we must have it," said her brother in an inflexible voice.

And compelled by his resolute manner, the girl, whom they had always regarded as a frivolous butterfly, embarked upon her strange and thrilling narrative.

"It all arose out of the sale of those letters I spoke to you about. Carrie just now asked me the name of the man who wrote them. Well, I didn't get further than Roddie, which doesn't carry you very far. If it had not been for your threat of going to Scotland Yard, I should have stopped at that. A still tongue makes a wise head, you know."

They could quite believe that. In spite of her ceaseless chatter, Iris had always been very reticent about her own affairs. She had seen next to nothing of her brother for a few years, not very much of Carrie Masters. And, on these occasions, she had always avoided, in a marked manner, any allusion to her private affairs.

"I told you of a soppy young chap who started to make love to me last year. I didn't care a snap for him, but he was very persistent, and at last wrote me most urgent letters imploring me to be his wife. His full name was Roderick Murchison, a member of the great brewing family; his father has been dead for some time, he died during the war, and Roddie came in for tons of money, although he was not the eldest son. I don't know if you have ever heard of him?"

No, neither Davis nor Carrie had known of the existence of such a young man. They had a hazy idea that there was a big brewing firm of that name, that was all.

"Well, as I say, I didn't care a snap for him, although he was awfully good and generous, overwhelmed me with, all kinds of lovely presents: rings, bracelets, fur coats, etc. In our life, you know, one accepts these things from the mugs who are gone on us without attaching very much importance to the fact."

It was evident that Miss Iris had struck out her own line of life, and made a very good thing out of it.

"Well, then, Roddie began to grow desperate, and declared he couldn't live without me. It was all so genuine that at last I began to think seriously of it. There were tons of money, and although I didn't cotton much to the sort of life I should have to lead as his wife, still there were worse things than being Mrs. Roderick Murchison, with the future well assured, and a handsome settlement."

Davis and his elder sister exchanged wondering glances. So this butterfly little girl, whom they had always regarded as rather shallow and feather-brained, had had this wonderful chance of marrying a gentleman and a rich man.

"It was difficult to bring myself up to the scratch, in spite of the advantages, for he was so soft and soppy that he irritated me in a thousand-and-one ways, and I knew in a very short time I should grow to hate and despise him. Then one night, after a very excellent champagne supper at the 'Excelsior,' he got me in a yielding mood, and I promised to marry him."

Brother and sister could only marvel at the girl's extraordinary good fortune, reluctant as she seemed to avail herself of it.

"He told me that before he went to bed that night he wrote to his family acquainting them with the news, anticipating fully their objections, but expressing his strong determination to brook no interference or remonstrance. You see he was his own master, nobody could take his money away from him, and he didn't care whether his relatives were offended or not."

"And how did the family take it?" queried Davis.

"I am coming to that," replied Iris. She was growing much calmer now. It was a relief to unburden her secret to an audience whom she could trust. For she was sure that neither her brother nor sister would ever allow her to put herself into real danger.

"I am coming to that," she repeated. "A few days after he had written those letters, one to his widowed mother, one to his elder brother, who had inherited the bulk of the big fortune, the elder brother called upon me in my flat. He was a very handsome, well-set-up man, although he had been through a good deal in the war. He was very like you, Reggie."

"Ah," ejaculated Mr. Davis. He looked at Carrie, keenly watching her sister, with a glance that suggested they would soon be coming to the real pith of this rambling confession.

"He begged the favour of a short conversation. He was perfectly open and above-board. He told me straight he was Roddie's elder brother, and that his name was Hugh Murchison. He pointed out to me very kindly that his brother was an impetuous young ass—a judgment which I privately endorsed—that Roddie had been infatuated, in his short day, with quite a number of other girls, although, perhaps, not to the same extent as with me." Iris, getting back rapidly into her light mind, let her volatile and easily impressed nature peep out in her next words.

"Oh, Hugh Murchison was a darling, so quiet, so sensible, and so strong. If he had been fool enough to ask me to marry him, I would not have given him up for seven thousand pounds."

"But you were prepared to chuck Roddie for that?" suggested her brother quietly.

"I think I let him go a bit too cheap," answered the fair Iris in a reflective voice. "Many girls have got more than I asked for compromising a breach of promise. But to tell the absolute truth, Hugh Murchison hypnotised me a bit. He was so quiet and yet so strong that I felt he could twist me round his little finger."

"We want to get to Cathcart Square," interjected Davis a little impatiently. "We don't seem to be near it yet."

"I must tell my story my own way, it is no use driving me," replied Iris, pouting a little. "Well, as I tell you, he called that day at my flat—that was the beginning of negotiations. Where were we to meet to discuss details? I couldn't have him at my flat, because Roddie was always popping in and out. He couldn't have me at his hotel, because nobody knew whom we might come across, and Roddie was always coming there. He said he would think out a plan and telephone or wire me."

"Ah," said Carrie, with a sigh of relief: she was a very practical person. "Now, I suppose we are coming to it."

Iris, heedless of the interruption, went on with her story.

"Next day he 'phoned me up, and after ascertaining that I was quite alone, told me to meet him at 10 Cathcart Square to resume our conversation."

"Why, in the name of all that is wonderful——" began Reginald Davis, but his sister motioned him to silence.

"Don't interrupt, please, you will know everything in a few minutes. I went to No. 10 Cathcart Square at the time appointed. He opened the door himself. It was a big house in an old-fashioned square, ages old, I should say, and in the front court was an agent's board, intimating that this particular house was to let, furnished."

"I know Cathcart Square well, it's in an old-world quarter of Kensington," interrupted Davis. He added grimly, "I know it well, although I did not have the misfortune to commit suicide there."

"He told me a very funny story. The afternoon of the day before, he had been up to Kensington to visit an old nurse of the family who lived near by. He had strolled round to Cathcart Square to fill up an idle half-hour. He had been struck by the appearance of the house, and loitered before it, when suddenly the door opened, and a somewhat bibulous-looking caretaker came out."

Davis indulged in a sigh of relief. "We are really coming to it now, then?"

"Yes, you are coming to it. He told me a sudden idea had occurred to him. Here would be a quiet little spot for our meetings, a place where Roddie would never dream of following us. He accosted the caretaker, evidently a drunken and corrupt creature. He explained that he wanted to rent a couple of rooms where he could receive a certain visitor he was expecting in the course of the next week or fortnight. It was no use going to the house agents for that, they would turn down such a proposition. The caretaker, with a couple of five-pound notes in his hand, took an intelligent view of the situation. He gave Hugh a key, and intimated that, if he had sufficient notice, he would make himself scarce on the occasions when the visitor was expected."

"Of all the mad things——" began Davis, but his sister for the second time motioned her brother to silence.

"Not quite so mad as you think. I fancy I can see into his mind. We could have met at a dozen different restaurants in London, but Roddie was here, there and everywhere: at any moment he might have come across us. He would never get as far as Kensington." David nodded his sagacious head. "I think I see. Go on."

"I met him there, in all four times, the last meeting was a few days before the tragedy."

"And what took place at that meeting?"

"He paid me the seven thousand pounds in notes. I signed a paper agreeing to give Roddie up. I carried out my bargain. I wrote Roddie that same night, giving him his dismissal, and assuring him that nothing he could urge would induce me to reconsider my determination. He sent me frantic telegrams the next day, but I replied to the same effect. After taking his seven thousand pounds, I could not break faith with Hugh, could I?"

Davis was not quite sure that Iris would not break faith with anybody if it suited her purpose. But clearly Hugh Murchison had subjugated her to the extent of respecting an honourable bargain. No doubt she had fallen in love with him, so far as a person of her shallow temperament could fall in love.

"And what has become of Roddie?"

"I don't know, and I don't care. He has bored me to extinction for over nine months. I am glad to be shut of him."

Davis put a question. "You say Hugh Murchison paid you in notes. What have you done with them? His bank will have the numbers."

"Will they?" cried Iris, the frightened look again coming into her eyes; she knew nothing of business methods. "I paid them into my own account. Now, you see, if you rake this up I might be implicated."

"Your opinion is, then, that the man found in No. 10 Cathcart Square was Hugh Murchison?"

"I am as nearly sure as I can be, after reading the caretaker's evidence. He had some other stunt on beside my own. I was not the only visitor he received."

Davis thought deeply before he spoke. "If I have him dug up, and he is identified by those who know him, a lot will come to light. Your notes will be traced, for one thing."

"I am afraid of everything, Reggie. For the love of Heaven, let him rest where he is." Caroline Masters breathed softly to herself. "You were half in love with him, or perhaps three-quarters, and you don't want to know the real truth. Oh, you miserable little, paltry soul!"

And then a sudden thought came to Davis. "Now, Iris, you could never think very clearly about things when they got a little bit complicated. You are quite sure the last occasion on which you saw him was a few days before the discovery of the body?"

"I will swear to it," cried Iris firmly.

"The date of his cheque, which the Bank has, will show that. He probably cashed it himself on the day he paid you, any way the day before. Now, on the day preceding and the day following that tragedy, can you prove where you were?"

Iris began to see light. "Of course I can. The day after I had the notes, I got up a sprained ankle, an obliging doctor, an old (or rather young) friend of mine, sent a certificate to the theatre. I motored down to Brighton with Johnny Lascelles—who, by the way, used to make Roddie fearfully jealous. We joined a jolly little party at 'The Old Ship.' I came back the day after the discovery in Cathcart Square."

Davis rose and gave a great shout: "You have witnesses who can swear to that?"

"Of course," answered Iris, not even yet comprehending the full drift of the question. "Johnny Lascelles motored me there and drove me back. Then there was Cissy Monteith, Katie Havard, Jack Legard and others who were with me all the time."

"You silly little idiot," cried Reginald Davis. "And what the deuce do you mean by saying that you might be implicated?"

"The notes," she faltered. "My meeting him alone in that empty house. They might suggest I murdered him, if you say he was murdered."

Davis smote his forehead in impotent anger at her denseness. "How could you have murdered him when you were at Brighton all the time?"

He smote the palms of his hands together.

"I will find out who the dead man was, and also the man who forged my name to that letter to the Coroner."

He turned to his sister: "As for you, young woman, it may be you will have a bad quarter of an hour, if it all comes out about Roddie. But never mind, you will have a splendid advertisement. The next bunch of letters you get hold of, the price will be twice seven thousand pounds."