As soon as the door had closed behind her Barbara crossed the hall quickly; but she did not return to her own apartments. She had made her plans while she listened to her uncle and Lord Rosmore. Now, she hurried along a corridor to a small door opening on to the terrace, hardly ever used except by herself when she went to talk to Martin in the tower. Between it and the ruins there was not much of the terrace to travel, and the shadows were deep. The sharpest eyes might fail to see a moving figure amongst them. Barbara ran lightly, her skirts gathered from her feet, and, entering the ruins, went quickly to the tower. The door was shut, but not locked, and she mounted the winding stairs to Martin's room. It was in darkness. "Martin!" she called softly, but there was no answer. Had Crosby got knowledge of his danger, and gone? Even now he might be in the hands of his enemies, for were not all the ways of escape watched to-night? What could she do? She stood for a few moments undecided how to act. She must not be found there by her uncle or Lord Rosmore who might seek her there if by chance they discovered that she had not returned to her own rooms. Almost certainly they would have her watched to-night. Yet she must stay to warn Martin and Gilbert Crosby, if by chance they were still ignorant of their danger. It would never do for them to be caught in the tower, from which there was no hope of escape. There was a small landing outside the room. At the top of the winding stairs there was a door, fastened back by a clamp, and Barbara had never known this door to be shut. Another winding stair led to the flat roof of the tower, where Martin often spent hours, reading the future in the stars, he said. She went to the roof now, but it was empty, and she came down again quickly. Perhaps they were sitting in the ruins, and had not heard her. She would go and see. As she descended a sound came to her--running feet--and through one of the narrow slits which gave a dim light to the stairs in daytime she discerned two men crossing the ruins. It was so dark in the tower that she could see them easily. They were not half-way across when other men came running from the terrace, but the fugitives could easily have reached the tower and closed the door upon their pursuers had not one of them caught his foot and fallen. It was Gilbert Crosby; he did not know every stone as Martin did. He was on his feet again directly, but the advantage had been lost. Barbara went down a little farther until she was just hidden by the first bend in the stairs. There was the sudden clash of steel, and a pistol-shot rang out upon the night. All was confusion in the doorway just below her. Then two men came up slowly, and backwards, thrusting downwards as they came, and more than one groan told that the steel had done its work. "Be ready to rush when I give the word," Martin whispered; "then, at the top, make a stand--we must close the door there somehow."