Johnstone of the Border by Harold Bindloss

Elsie went to sleep at last, but her rest was broken and once or twice she awoke with a start. She was uneasy and highly strung, but she heard nothing unusual. The wind moaned about the house and the splash of the little burn rose from the glen. Staffer had gone out before dinner and as he had not come back when she went to bed, she did not think any stranger would visit Appleyard. Telling herself that she must not indulge in nerves, she went to sleep again. Some time later, when lying half awake, she heard a soft rattle; and her heart beat fast, for she knew that the handle of her door was being gently turned. She was glad that she had locked it, though this was the first time she had ever done so.

The sound stopped, a board in the passage creaked, and as the shock of alarm began to pass, Elsie guessed that it was Staffer trying to make sure that she was in her room. This implied that he was going downstairs to meet some one; but she waited until she got calmer, wondering if, after all, she had been mistaken. Staffer could not have returned until late, and it was strange he had allowed his visitor to risk coming to the house when he might be out. She tried to believe he had not done so; but when she heard a faint tap on the other door, which opened into Madge's room, there was no longer any doubt. Nerving herself for a painful effort, she got up and hastily put on some clothes. Then she went into the other room and saw Madge's shadowy figure standing by the window.