If chance there was, that chance must be under cover of night--night, when she was at least free from the espionage of human eyes. How could she get out of the house undetected and get back into it unsuspected? And if she could accomplish this well-nigh impossible feat, how arrange to meet Roger--when she could not communicate with him, when she did not even know where he lived? Every system of human devising has its weak point. By observing and thinking Beatrice discovered the weak point in this system of her father’s. As soon as she formed her plan she got ready this note: _Chang_: It is absolutely necessary that I see you for a few minutes. My only chance is at night. So, come down to the cascade at one o’clock the morning after you get this. Don’t fail me. Don’t think me hysterical or sentimental. I might almost say this is a matter of life and death. RIX. The burglar alarms were switched on every night by Conrad Pinney, the superintendent, just after the house was closed. They were switched off at five in the morning by Tom, the indoors watchman, when the lowest rank of menials in the service of the establishment descended from their little rooms under the eaves of the west wing to make ready the first-floor rooms for the day. The house was closed as soon as the last member of the family went up to his or her rooms. To escape, she must choose the moment or so between the ascending of the last member of the family and the switching on of the alarms--and it must be on a night when some one member of the family stayed down long enough after the going of the rest to make it certain there would be no accidental glancing into her rooms to see that all was well. To get back into the house she must wait until it was opened at five o’clock and slip in unseen by the menial sweepers and cleaners and polishers.