“And,” I put in, “a plunger doesn’t always make the best of husbands.  Perhaps there is temperament to be reckoned with here.”

“There seem to be a good many things to be reckoned with,” Craig considered.  “For example, here’s a houseboat, the Lucie, a palatial affair, cruising about aimlessly, with a beautiful woman on it.  She gives a little party, in the absence of her husband, to her brother, his fiancee and her mother, who visit her from his yacht, the Nautilus.  They break up, those living on the Lucie going to their rooms and the rest back to the yacht, which is anchored out further in the deeper water of the bay.

“Some time in the middle of the night her maid, Juanita, finds that she is not in her room.  Her brother is summoned back from his yacht and finds that she has left this pathetic, unfinished letter.  But otherwise there is no trace of her.  Her husband is notified and hurries out there, but he can find no clue.  Meanwhile, Mr. Waldon, in despair, hurries down to the city to engage me quietly.”

“You remember I told you,” suggested Waldon, “that my sister hadn’t been feeling well for several days.  In fact it seemed that the sea air wasn’t doing her much good, and some one last night suggested that she try the mountains.”

“Had there been anything that would foreshadow the—­er—­ disappearance?” asked Kennedy.

“Only as I say, that for two or three days she seemed to be listless, to be sinking by slow and easy stages into a sort of vacant, moody state of ill health.”

“She had a doctor, I suppose?” I asked.

“Yes, Dr. Jermyn, Tracy’s own personal physician came down from the city several days ago.”

“What did he say?”

“He simply said that it was congestion of the lungs.  As far as he could see there was no apparent cause for it.  I don’t think he was very enthusiastic about the mountain air idea.  The fact is he was like a good many doctors under the circumstances, noncommittal—­ wanted her under observation, and all that sort of thing.”

“What’s your opinion?” I pressed Craig.  “Do you think she has run away?”

“Naturally, I’d rather not attempt to say yet,” Craig replied cautiously.  “But there are several possibilities.  Yes, she might have left the houseboat in some other boat, of course.  Then there is the possibility of accident.  It was a hot night.  She might have been leaning from the window and have lost her balance.  I have even thought of drugs, that she might have taken something in her despondency and have fallen overboard while under the influence of it.  Then, of course, there are the two deductions that everyone has made already—­either suicide or murder.”

Waldon had evidently been turning something over in his mind.

“There was a wireless outfit aboard the houseboat,” he ventured at length.

“What of that?” I asked, wondering why he was changing the subject so abruptly.