“What was the truth about her father?” he said doggedly.  “He was eccentric; was he ever worse than that?”

“The truth was that he became mentally irresponsible before his death.”

“You know this?”

“Alixe told me when we were schoolgirls.  And for days she was haunted with the fear of what might one day be her inheritance.  That is all I know, Phil.”

He nodded and for a while made some pretence of eating, but presently leaned back and looked at his sister out of dazed eyes.

“Do you suppose,” he said heavily, “that she was not entirely responsible when—­when she went away?”

“I have wondered,” said Nina simply.  “Austin believes it.”

“But—­but—­how in God’s name could that be possible?  She was so brilliant—­so witty, so charmingly and capriciously normal—­”

“Her father was brilliant and popular—­when he was young.  Austin knew him, Phil.  I have often, often wondered whether Alixe realises what she is about.  Her restless impulses, her intervals of curious resentment—­so many things which I remember and which, now, I cannot believe were entirely normal. . . .  It is a dreadful surmise to make about anybody so youthful, so pretty, so lovable—­and yet, it is the kindest way to account for her strange treatment of you—­”

“I can’t believe it,” he said, staring at vacancy.  “I refuse to.”  And, thinking of her last frightened and excited letter imploring an interview with him and giving the startling reason:  “What a scoundrel that fellow Ruthven is,” he said with a shudder.

“Why, what has he—­”

“Nothing.  I can’t discuss it, Nina—­”

“Please tell me, Phil!”

“There is nothing to tell.”

She said deliberately:  “I hope there is not, Phil.  Nor do I credit any mischievous gossip which ventures to link my brother’s name with the name of Mrs. Ruthven.”

He paid no heed to what she hinted, and he was still thinking of Ruthven when he said:  “The most contemptible and cowardly thing a man can do is to fail a person dependent on him—­when that person is in prospective danger.  The dependence, the threatened helplessness must appeal to any man!  How can he, then, fail to stand by a person in trouble—­a person linked to him by every tie, every obligation.  Why—­why to fail at such a time is dastardly—­and to—­to make a possible threatened infirmity a reason for abandoning a woman is monstrous—!”

“Phil!  I never for a moment supposed that even if you suspected Alixe to be not perfectly responsible you would have abandoned her—­”

“I? Abandon her!” He laughed bitterly.  “I was not speaking of myself,” he said. . . .  And to himself he wondered:  “Was it that—­after all?  Is that the key to my dreadful inability to understand?  I cannot—­I cannot accept it.  I know her; it was not that; it—­it must not be!”

And that night he wrote to her: