She followed on steadily through the gloom of the trees, depending on the glint of the white dress to keep her right. The wood began to thicken, and presently, when the road widened and the trees grew farther back, she lost sight of any indication of her whereabouts. Under the present conditions it was impossible for her to do any more, so, after waiting for a while, still hidden in the shadow to see if she could catch another glimpse of the white frock, she determined to go on slowly towards Castra Regis, and trust to the chapter of accidents to pick up the trail again. She went on slowly, taking advantage of every obstacle and shadow to keep herself concealed. At last she entered on the grounds of the Castle, at a spot from which the windows of the turret were dimly visible, without having seen again any sign of Lady Arabella. Meanwhile, during most of the time that Mimi Salton had been moving warily along in the gloom, she was in reality being followed by Lady Arabella, who had caught sight of her leaving the house and had never again lost touch with her. It was a case of the hunter being hunted. For a time Mimi's many turnings, with the natural obstacles that were perpetually intervening, caused Lady Arabella some trouble; but when she was close to Castra Regis, there was no more possibility of concealment, and the strange double following went swiftly on. When she saw Mimi close to the hall door of Castra Regis and ascending the steps, she followed. When Mimi entered the dark hall and felt her way up the staircase, still, as she believed, following Lady Arabella, the latter kept on her way. When they reached the lobby of the turret- rooms, Mimi believed that the object of her search was ahead of her. Edgar Caswall sat in the gloom of the great room, occasionally stirred to curiosity when the drifting clouds allowed a little light to fall from the storm-swept sky. But nothing really interested him now. Since he had heard of Lilla's death, the gloom of his remorse, emphasised by Mimi's upbraiding, had made more hopeless his cruel, selfish, saturnine nature. He heard no sound, for his normal faculties seemed benumbed. Mimi, when she came to the door, which stood ajar, gave a light tap. So light was it that it did not reach Caswall's ears. Then, taking her courage in both hands, she boldly pushed the door and entered. As she did so, her heart sank, for now she was face to face with a difficulty which had not, in her state of mental perturbation, occurred to her. CHAPTER XXVII--ON THE TURRET ROOF