Possessed by the belief that her sister, either alive or dead, was hidden somewhere inside the Hall, poor Susan, as we already know, whenever she could escape her mother's vigilance, took to wandering about the grounds in the dusk of evening, gazing up at the windows of the old house, more especially at her sister's bedroom window, often fancying that she heard Katherine's voice calling her, and trying everywhere to find some traces of the missing girl. After a time the thought seemed to have entered her head that if she could only get inside the Hall and search there, it would be better still. It would appear that on two occasions during Katherine's service there, when Susan had gone up to the Hall hoping to see her sister, Aaron Stone had locked up for the night. Susan had then thrown some pieces of gravel at her sister's window, in order to attract attention; upon which Katherine had come out to her, kissed her, and bidden her to return home. Susan, curious to know by what means her sister had been able to leave the house after it was made safe for the night, had persuaded Katherine to tell her.

Among other rooms on the ground-floor at the back of the Hall, or rather at its side, and the side not frequented, was one that was called the wood-room, in which logs were kept to dry for winter burning. The unglazed window of this room was protected by horizontal iron bars; and one day, by a mere accident, Katherine saw that the lowest bar was loose in its socket; it could be displaced and replaced at will, and there was not the smallest difficulty in stepping through the low aperture to the ground outside. Katherine had thought it no harm to make use of this discovered means of egress on the one or two occasions she had seen her poor simple sister waiting, rather than let the girl remain there, as she might have done, for half the nights When the loss came, poor Susan never spoke of this, lest it might bring blame on Katherine's memory.

But she did not forget it. And when, impelled by uncontrollable longing to discover a clue to her sister's fate and to venture inside the house, she sought for the window, she readily found it. She had but to displace the bar, step in, and be within the Hall. Near the door of the wood-room was a narrow, back staircase, hardly ever used, which led up to the north wing, and so to the bedroom which Katherine had occupied.

Susan Keen might be half-witted, but she was cunning in this search. As she had found a way of getting into the Hall, so she found a way of getting out of her mother's house. After she was supposed to be safe in bed, she would creep downstairs, open one of the lower windows, go out of it, and return in the same way, Mrs. Keen being none the wiser. She made for herself a pair of list shoes which she slipped on over her ordinary walking shoes whenever she ventured, which was but rarely, inside the Hall. Between the two sisters there was a strong family likeness; both had the same long, pale, serious face, the same large, grey eyes, and hair of the same tint--a dark brown with a gleam of gold in it. In the dusk of evening or by the dim light of a candle in a big room, it was quite possible that one sister should be mistaken for the other, even by those to whom both of them were well known. Susan it was whom the two maids, Ann and Martha, had seen looking down upon them from the gallery; she it was who had frightened Mrs. Carlyon and deceived Maria Kettle; it was her voice that Conroy had heard calling for her sister as she wandered through the dark passages of the north wing; it was she who had tried Betsy Tucker's door the night of the storm: and it was no other than she who had rearranged the furniture in Katherine's abandoned chamber, about which there had been so much speculation. The supposed ghost, haunting the north wing, had not been a ghost after all; instead of being Katherine dead, it was Susan living.

"But she will not come to me, though I seek for her everywhere," wailed poor Susan, as she came to the end of her narrative and looked piteously into the compassionate face of Miss Winter. "Oh, ma'am, where can she be? Living or dead, she must be inside these walls. I hear her voice calling to me, but I can never find her. Where can she be? where can she be?"

It was a question that Miss Winter could not answer.

[CHAPTER XIII.]

THE LAST MYSTERY SOLVED

"It's not a bit of use your making any objection, my dear. I've set my mind on it, and I mean to do it. Why should you wait till I'm dead? I may live for a dozen years to come, and the income will be of far more use to you now when you are setting up housekeeping than it would be later."

The speaker was Lady Maria Skeffington, and the person to whom she was laying down the law in this peremptory fashion was her god-daughter, Maria Kettle--or rather Mrs. Cleeve. Maria and Philip had moved into a pretty little house near Homedale; they were furnishing it and beginning life on their own account. Maria had a large apron on, and her gown-sleeves turned up at the wrists; she was making herself as busy as a bee this morning, with her two maid-servants, when interrupted by her godmother.