The whistle came again, and again, in spite of her relentless spurring, her horse checked his pace. A sudden inspiration came to her. Perhaps it was the horse she was riding that was the cause of all the trouble. It was certainly the Arab's whistle that had made it moderate its speed; it was responding clearly to a signal that it knew. Her guide's reluctance to give any particulars of his acquisition of the horse came back to her. There could not be much doubt about it. The animal had unquestionably been stolen, and either belonged to or was known to the party of Arabs who had met them.
The naivete that paraded a stolen horse through the desert at the risk of meeting its former owner made her smile in spite of her annoyance, but it was not a pleasant smile, as her thoughts turned from the
