And Courtney gave the answer vaguely, for the waltz was ended, and the Princess Ziska, on the arm of Gervase, was leaving the ball-room.

“She’s going,” exclaimed Lady Fulkeward. “Dear creature! Excuse me—I must speak to her for a moment.”

And with a swish of her full skirts and a toss of her huge hat and feathers, the lively flirt of sixty tripped off with all the agility of sixteen, leaving Courtney to follow her or remain where he was, just as he chose. He hesitated, and during that undecided pause was joined by Dr. Maxwell Dean.

“A very brilliant and interesting evening!” said that individual, smiling complacently. “I don’t remember any time when I have enjoyed myself so thoroughly.”

“Really! I shouldn’t have thought you a man to care for fancy-dress balls,” said Courtney.

“Shouldn’t you? Ha! Well, some fancy-dress balls I might not care for, but this one has been highly productive of entertainment in every way, and several incidents connected with it have opened up to me a new vista of research, the possibilities of which are—er—very interesting and remarkable.”

“Indeed!” murmured Courtney indifferently, his eyes fixed on the slim, supple figure of the Princess Ziska as she slowly moved amid her circle of admirers out of the ball-room, her golden skirts gleaming sun-like against the polished floor, and the jewels about her flashing in vivid points of light from the hem of her robe to the snake in her hair.

“Yes,” continued the Doctor, smiling and rubbing his hands, “I think I have got the clue to a very interesting problem. But I see you are absorbed—and no wonder! A charming woman, the Princess Ziska—charming! Do you believe in ghosts?”

This question was put with such unexpected abruptness that Courtney was quite taken aback.

“Ghosts?” he echoed. “No, I cannot say I do. I have never seen one, and I have never heard of one that did not turn out a bogus.”