When the driver found himself signaled he reined up, then came to the cab door.

“You know where to go?” she said.

“Yes,” nodded the man.

“Drive there, then.”

The driver whipped up his horses to a better speed, the vehicle bowling along now.

“I very much fear that I am running you into danger,” declared Daisy Huston, soberly.  “Mr. Benson, if you decide to leave the cab, or to have me take you back to the center of the city, I shall not imagine you to be lacking in courage.”

“I cannot be in any greater danger than you are, Miss Huston,” Benson ventured, with a smile.

“Oh, it is much different in my case,” argued the girl.  “Donald Graves would not attack a woman, especially the woman he had professed to love.”

“Miss Huston, do you feel like discussing this matter any further?” hazarded the young acting naval lieutenant.

“Yes; as much as you wish.”

“I confess to being a bit curious.”

“About what?”

“Did Millard—­Graves, I mean, have any great reason to need money?  More, I mean, than he could earn by honest work?”

“Yes,” admitted Miss Daisy.  “My mother is dead.  Under her will I inherit a considerable little fortune when I am twenty-five.  But it is solely on condition that I have my father’s permission to marry the man of my choice.  I could remain single until twenty-five, but I am only nineteen, and Mr. Graves complained that it would be an eternity to wait.”

“Then your father did not approve Millard?  I am going to call him that because the other name is unfamiliar.”

“My father feared that Donald was a fortune hunter.  He said he would be satisfied if Donald could show that he were rich in his own name.”

“So, then, Graves, or Millard, hit upon the plan of stealing our harbor fortification secrets and selling them to another government,” said Jack, meditatingly.  “Yet I am puzzled to understand how he found the chance.  There are no foreigners openly engaged in buying our national secrets.”

“I think I can explain all that, though it will be but guess-work,” replied Daisy Huston, thoughtfully.  “My father was for some years minister to Sweden.  He is still well acquainted among foreign diplomats here in Washington.  Some of them are often at our house.  Donald must have met one there who tempted him, or pointed the way to a fortune.  Yes; I am certain that must be the answer.”

“Did—­but perhaps you don’t like my asking such questions?”

“No; I do not mind—­now,” replied Daisy Huston.  “I began to feel as though I had been an innocent party to Donald Graves’s wrongdoing.  When I went to try to see you, this afternoon, I supposed only that Donald had gotten into trouble through some filibustering expedition to Central America.  I did not look upon that as so serious, you see.  But selling the national secrets is quite another matter,” she added, bitterly.  “I shall never care for the man again.  I have wrenched him from my heart in these last few minutes.  So you may ask me any questions that will help to clear up the matter.”