A World of Girls by L.T. Meade

Hester stayed behind in the shady little arbor, and then, on that soft spring day, while the birds sang overhead, and the warm light breezes came in and fanned her hot cheeks, good angels and bad drew near to fight for a victory. Which would conquer? Hester had many faults, but hitherto she had been honorable and truthful; her sins had been those of pride and jealousy, but she had never told a falsehood in her life. She knew perfectly -- she trembled as the full knowledge overpowered her -- that she had it in her power to exonerate Annie. She could not in the least imagine how stupid Susan Drummond could contrive and carry out such a clever and deep-laid plot; but she knew also that if she related what she had seen with her own eyes the night before, she would probably give such a clue to the apparent mystery that the truth would come to light.

If Annie was cleared from this accusation, doubtless the old story of her supposed guilt with regard to Mrs. Willis' caricature would also be read with its right key. Hester was a clever and sharp girl; and the fact of seeing Susan Drummond in the school-room in the dead of night opened her eyes also to one or two other apparent little mysteries. While Susan was her own room-mate she had often given a passing wonder to the fact of her extraordinary desire to overcome her sleepiness, and had laughed over the expedients Susan had used to wake at all moments.