Then again, it seemed strange that the letter had never been posted. Why had he not received it on the Thursday morning? He could quite understand that it was possible for his father, having addressed the two envelopes at the same time, to have put the wrong enclosure in each; thus sending the letter to his son to Makepeace, and at the same time forwarding to himself the blank sheet of foolscap intended for the bookseller. But supposing this to have been the case, why, then, were not both letters posted? Why was one sent and the other kept back? And why, being kept back, was the letter placed in the safe?

The Captain meditated for a long time over this difficult question, and then attempted to explain it to himself in this way. He supposed that, after the two letters were closed and ready for the post, they lay together on the library table, that after a time some one, probably his father himself, took up the one addressed to Makepeace and put it into the letter-bag; but that the other letter, addressed to himself, was inadvertently left behind and forgotten, being covered up at the time, perhaps, by something on the table.

That subsequently, late at night and after the post-bag had gone to the lodge, his father discovered that he had omitted to post it; and that then, inasmuch as the letter contained matter of a private nature, he did not care to leave it lying on the table, but had carried it up with him to bed, and in accordance with his usual caution and suspicion had placed it in the safe until the morning. That then, on the Thursday, before he had opportunity to post it, the telegram arrived and his sudden illness occurred; and that consequently the letter written the day before was left in the safe; that then he had appeared on the scene, and of course his father, having no longer any occasion to post the letter, had merely called his attention to it and told him where it had been placed.

The Captain went up to bed that night feeling considerably relieved that the communication in the letter was, after all, of so harmless a nature. He had evidently been making much ado about nothing; the so-called mystery had turned out to be most easy of solution and had nothing very mysterious about it.

But as he lay awake thinking of it all, and only half satisfied with the explanation that he had worked out with so much care, two unanswerable problems suggested themselves to him, and made him feel that, after all, he had by no means got to the bottom of the strange occurrence, and that there still remained much that was mysterious and suspicious.

For, in the first place, was it likely that his father, having written a letter to him on ordinary note-paper, would place it, when written, in a foolscap envelope? The very size of the sheet would prevent his making the mistake which he had thought it possible that he might have made.

And, moreover—and this latter problem he felt was by far the greater one—why was the letter to himself addressed in the way it was? Did it not say on the envelope, "For my son—to be opened after my death?" His father would never have addressed it in that way, had he intended to post it.

What did it all mean? His former theory was entirely upset by the remembrance of this fact. He felt that he had not worked out the solution correctly after all.

Kenneth Fortescue's brain felt in a whirl; the longer he puzzled over it, the more hopelessly bewildered he became. All night long he was struggling to find some possible explanation which might prove satisfactory in all points, but he utterly failed to discover one.

Tired in mind and body, he rose in the morning determined to lay the whole matter before his father's lawyer. He went to Mr. Northcourt's office, and took him entirely into his confidence; but neither he nor the lawyer were able to come to any conclusion as to what had happened with regard to the two letters.