“You are a good friend, Billie, and I’m going to give your friend the benefit of every doubt in her favor.  I’m going to assume that she is innocent and that there is some big mistake somewhere.  But I want you to help me because it will be necessary to get at the bottom of the business immediately.  Now, Yoritomo Ito is one great big fanatic.  I discovered that the other day when he called here in his foolish garb and demanded the hand of Miss Nancy.  He was very angry over being turned down and just a bit threatening in his manner.  Of course he resents outside people being called in for the work I am doing.  He resents my presence in his country, in fact.”

“I don’t like him, Papa,” broke in Billie, “and—­you didn’t know that he has been married and divorced?”

Mr. Campbell looked surprised.

“No, indeed, I did not know it.  He has colossal nerve, I must say.  But divorce is pretty common over here.  Most anybody can get one who wants to.”

“And, Papa,” went on Billie, “I believe that our little maid, Onoye, was his wife, and when her father lost his money, Yoritomo got a divorce, and she and her mother were so poor they had to go to work.”

Mr. Campbell was even more shocked at this disclosure.

“And, Papa, I believe she would do most any favor for Yoritomo in order to get to see her little boy who lives with Mme. Ito.  Onoye and her mother are mad about him, and—­and—­” went on Billie, slowly working out the complication in her mind—­“they were the ones who laid the blame on Nancy, weren’t they?”

“I didn’t know I had a detective for a daughter,” said Mr. Campbell, smiling.

“I’m just putting two and two together,” said Billie.  “You see it works out like a jigsaw puzzle.”

“So I see,” said Mr. Campbell gravely.  “There is only one bright spot in the whole business,” he added, with something very like a chuckle.  “For once in my life I’ve out-tricked a trickster and I’ve really enjoyed doing it.  Buxton informed me the very night you shot somebody here—­”

“There you are,” interrupted Billie.  “That was Onoye, remember.”

“Yes, there is no doubt about that.  Well, Buxton informed me that they were after my papers and the safe would be the place they would look for them.  So that very night I substituted some old drawings and put the important ones in another place.  Now a Japanese, when he’s after something, is as crafty and shrewd as a fox.  That’s why I’m patting myself on my back for having outwitted one.”

“Where do you keep the real papers, Papa?”

“Down where the pistol is under some stationery in the back of the desk drawer, and in the big vase in the corner.”

Billie went straight to the desk and opened the drawer.  She drew out the pistol as she had done that dark night, removed several layers of envelopes and paper, and came at last to a layer of drawings.

“Are these the ones?” she asked, placing them on the desk and then shoving the drawer back with her knee.  Something stuck and she pulled it all the way out in her effort to discover what the trouble was.  In the very back, caught between the drawer and the framework was a handkerchief.  It was small and sheer and in one corner was an embroidered butterfly.