midnight
This drawer I beg of you to carry back with you to Cavendish Square exactly as it stands . `` That is the first part of the service : now for the second . You should be back , if you set out at once on the receipt of this , long before midnight ; but I will leave you that amount of margin , not only in the fear of one of those obstacles that can neither be prevented nor foreseen , but because an hour when your servants are in bed is to be preferred for what will then remain to do . At midnight , then , I have to ask you to be alone in your consulting-room , to admit with your own hand into the house a man who will present himself in my name , and to place in his hands the drawer that you will have brought with you from my cabinet . Then you will have played your part and earned my gratitude completely . Five minutes afterwards , if you insist upon an explanation , you will have understood that these arrangements are of capital importance ; and that by the neglect of one of them , fantastic as they must appear , you might have charged your conscience with my death or the shipwreck of my reason . `` Confident as I am that you will not trifle with this appeal , my heart sinks and my hand trembles at the bare thought of such a possibility .