Bab did not return her look or make any answer.

A little while later Barbara disappeared.  She went back alone to Mr. Hamlin’s study.  On top of his desk she discovered a box about a foot and a half long.  It had been opened and a key was lying beside it on the desk.  Barbara could see that there was no money in the box, only a collection of papers.  Bab returned the long envelope, which she had found at Mrs. Wilson’s feet in the hall to its place, turned the key in the lock of the box, and then carried the key upstairs, intending to hand it over to Harriet.  But Bab did not know whether or not she ought to explain to Harriet how she had come by the key.

Harriet was in the room with Mrs. Wilson, seeing her guest to bed for the second time, when Barbara went upstairs.  Bab had no desire to face Mrs. Wilson again that night.  The distrust of the woman that was deepening in the girl’s mind was too great to conceal.

“Come into my room in the morning before breakfast, Harriet, dear,” Mrs. Wilson entreated, as she kissed her young hostess good night.  “I know you will forgive my foolishness, when I have had a little talk with you.  It is too late now for explanations.”

It was between two and three o’clock in the morning before the household of the Assistant Secretary of State again settled itself to sleep.  Under her pillow Barbara Thurston had the key to Mr. William Hamlin’s strong box, in which valuable state papers were sometimes temporarily placed.

CHAPTER XVIII

A TANGLED WEB OF CIRCUMSTANCE

Harriet Hamlin spent half an hour in the room with Mrs. Wilson before she came down to the breakfast table the next morning.

“It is all right, girls,” she announced promptly, as soon as the maid left the room.  “Mrs. Wilson is going to have her breakfast in bed.  She is a little upset by the happenings of last night.  But she has explained everything to me.  For some time, Mrs. Wilson has been trying to play a joke on Father, and last night she made another attempt.  I promised her none of us would mention to him what had occurred.  Will you give me your word, all of you, not to tell?”

“Certainly, Harriet,” Ruth agreed seriously.  The other three “Automobile Girls” quietly nodded their heads.

“I don’t know that I quite approve of Mrs. Wilson’s method of practical joking,” Harriet went on.  “She frightened all of us.  But then, if no one had discovered her, no harm would have been done.”

Mollie and Grace gazed at Harriet, without trying to conceal their surprise, but Ruth and Bab only looked steadfastly at their plates.

“Father is so strict and good all the time, I just wish somebody would play a trick on him,” Harriet went on angrily.  She was annoyed at the attitude of the “Automobile Girls,” and she was still smarting under the hurt of her father’s speech the night before.  As long as her father had refused her money before she had even asked him for it, Harriet had decided that it would be worse than useless to appeal to him again.  She was now waiting for disaster to break over her head.