"You will go to her room, and remain with her till you hear from us. If she is awake, encourage her to sleep. She must know nothing till daylight. Should it be needed call to us for assistance."
"Yes, yes."
"You will show us the rooms in which your master and his friend from London sleep, and you will then leave us." Ronald turned to us. "I and my uncle will keep watch outside Mr. Nisbet's door; if he comes out to us I shall know how to deal with him. You, Mr. Rivers and Mr. Emery, will introduce yourselves to Dr. Cooper, and endeavor to force a confession from him. If he will not speak--well, you are a match for him. Bind him, so that he shall be unable to move; then join us, and we will make Mr. Nisbet secure. He must administer no more stupefying drugs to his stepdaughter; his power over her is at an end. Have you any objection to my plan, Mr. Rivers?"
"None. It is the best that can be adopted. Let us set about it."
With noiseless footsteps we ascended the stairs to the sleeping apartments, Mme. Bernstein leading the way. She pointed out the rooms to us. "That is the master's; that is his friend's." Then she left us, and went to Beatrice's room. Bob and Ronald took their station outside Mr. Nisbet's door and I observed that Bob held his revolver in his hand. No indication reached us that we had disturbed the inmates.
"It is our turn, now," Rivers whispered to me. "I think I know how to manage our customer."
He tried the door, and finding it locked, smiled as he said, "Locks himself in. Doesn't trust his host. A good sign." He did not knock, but kept fumbling at the handle, in order to attract Dr. Cooper's attention. Presently succeeding, we heard the doctor get out of bed.
"Who is there?" he asked softly, his ear at the door.
"Let me in," Rivers replied, in a whisper. "I have something to say to you. Why do you lock your door?"
Had Rivers spoken above a whisper Dr. Cooper would have detected him, but whispers are very much alike, and it is not easy to distinguish a man's voice by them.