“Supposing a man landed about the coast, here,” asked Mr. Lindsey—­“I’m just putting a case to you—­and didn’t go into the town, but walked along the beach—­where would he strike a railway station, now?”

The police official replied that there were railway stations to the right and left of the bay—­a man could easily make Edinburgh in one direction, and St. Andrews in the other; and then, not unnaturally, he was wanting to know if Mr. Lindsey was suggesting that Sir Gilbert Carstairs had sailed his yacht ashore, left it, and that it had drifted out to sea again?

“I’m not suggesting anything,” answered Mr. Lindsey.  “I’m only speculating on possibilities.  And that’s about as idle work as standing here talking.  What will be practical will be to arrange about this yacht being locked up in some boat-house, and we’d best see to that at once.”

We made arrangements with the owner of a boat-house to pull the yacht in there, and to keep her under lock and key, and, after settling matters with the police to have an eye on her, and see that her contents were untouched until further instructions reached them from Berwick, we went off to continue our journey.  But we had stayed so long in Largo that when we got to Edinburgh the last train for Berwick had gone, and we were obliged to turn into an hotel for the night.  Naturally, all our talk was of what had just transpired—­the events of the last two days, said Mr. Lindsey, only made these mysteries deeper than they were before, and why Sir Gilbert Carstairs should have abandoned his yacht, as he doubtless had, was a still further addition to the growing problem.

“And I’m not certain, my lad, that I believe yon man Robertson’s tale,” he remarked, as we were discussing matters from every imaginable point of view just before going to bed.  “He may have brought the yacht in, but we don’t know that he didn’t bring Carstairs aboard her.  Why was that change of clothes made?  Probably because he knew that he’d be described as wearing certain things, and he wanted to come ashore in other things.  For aught we know, he came safely ashore, boarded a train somewhere in the neighbourhood, or at Largo itself—­why not?—­and went off, likely here, to Edinburgh—­where he’d mingle with a few thousand of folk, unnoticed.”

“Then—­in that case, you think he’s—­what, Mr. Lindsey?” I asked.  “Do you mean he’s running away?”

“Between you and me, that’s not far from what I do think,” he replied.  “And I think I know what he’s running away from, too!  But we’ll hear a lot more before many hours are over, or I’m mistaken.”

We were in Berwick at an early hour next morning, and we went straight to the police station and into the superintendent’s office.  Chisholm was with Mr. Murray when we walked in, and both men turned to us with eagerness.

“Here’s more mystery about this affair, Mr. Lindsey!” exclaimed Murray.  “It’s enough to make a man’s wits go wool-gathering.  There’s no news of Sir Gilbert, and Lady Carstairs has been missing since twelve o’clock noon yesterday!”