“No—nothing.” The answer came quickly and with a show of spirit. “I have merely been wondering—testing every possibility. I dared not be too sanguine without some assurance. Pure logic is all very well for principles that do not touch us personally. But where one’s own safety is concerned the imperfect human mind demands visual evidence.”

“Ah, yes.” Vance looked up, and I thought I detected a flash of understanding between these two disparate men.

Markham rose to make his adieu; but Professor Dillard urged him to remain a while.

“Sigurd will be here before long. He’d enjoy seeing you again. As I said, he’s at ‘The Pretenders,’ but I’m sure he will come straight home. . . . By the way, Mr. Vance,” he went on, turning from Markham; “Sigurd tells me you accompanied him to ‘Ghosts’ last week. Do you share his enthusiasm for Ibsen?”

A slight lift of Vance’s eyebrows told me that he was somewhat puzzled by this question; but when he answered there was no hint of perplexity in his voice.

“I have read Ibsen a great deal; and there can be little doubt that he was a creative genius of a high order, although I’ve failed to find in him either the æsthetic form or the philosophic depth that characterizes Goethe’s ‘Faust,’ for instance.”

“I can see that you and Sigurd would have a permanent basis of disagreement.”

Markham declined the invitation to stay longer, and a few minutes later we were walking down West End Avenue in the brisk April air.

“You will please take note, Markham old dear,” observed Vance, with a touch of waggishness, as we turned into 72nd Street and headed for the park, “that there are others than your modest collaborator who are hag-ridden with doubts as to the volition of Pardee’s taking-off. And I might add that the professor is not in the least satisfied with your assurances.”

“His suspicious state of mind is quite understandable,” submitted Markham. “These murders have touched his house pretty closely.”