“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 celebre 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.