“Well, because she was all right till she had a cup of tea. I must take you into my confidence,” he said, lowering his voice. “She is a detective, brought down here to look after my guests. There have been a number of robberies committed lately by a woman who calls herself ‘Four Square Jane,’ and, to be on the safe side, I had this girl down to protect the property of my friends. When I saw her before dinner she was as well as you or I; then a cup of tea was given to her, and immediately she had these shiverings.” The doctor nodded thoughtfully. “It is curious you should say that,” he said; “for though she has the symptoms of scarlet fever, she has others which are not usually to be found in scarlet fever cases. Do you suggest that this woman, this Four Square person, is in the house?” “Either she or her agent,” said Mr. Lewinstein. “She has several people who work with her by all accounts.” “And you believe that she has given this girl a drug to put her out of the way?” “That’s my idea.” “By jove!” said the young man, “that’s rather a scheme. Well, anyway, there will be plenty of people knocking about to-night, so your guests will be safe for to-night.” The girl had been housed in the servants’ wing, but fortunately in a room isolated from all the others. Mr. Lewinstein made several trips upstairs during the course of the evening, saw through the open door the doctor sitting by the side of the bed, and was content. His guests retired towards one o’clock and the agitated Mrs. Lewinstein, to whom the news of the catastrophe had been imparted, having been successfully induced to go to bed, Mr. Lewinstein breathed more freely. At half-past one he made his third visit to the door of the sick room, for he, himself, was not without dread of infection, and saw through the open door the doctor sitting reading a book near the head of the bed. He stole quietly down, so quietly that he almost surprised a slim figure that was stealing along the darkened corridor whence opened the bedrooms of the principal guests. She flattened herself into a recess, and he passed her so closely that she could have touched him. She waited until he had disappeared, and then crossed to one of the doors and felt gingerly at the key-hole. The occupant had made the mistake of locking the door and taking out the key, and in a second she had inserted one of her own, and softly turning it, had tip-toed into the room. She stood listening; there was a steady breathing, and she made her way to the dressing-table, where her deft fingers began a rapid but silent search. Presently she found what she wanted, a smooth leather case, and shook it gently. She was not a minute in the room before she was out again, closing the door softly behind her.