midnight
`` Should anything occur to detain us in our ride , let this packet be given to Mrs. Headley . Mind , Sergeant , certainly not before midnight . '' `` Your command shall be obeyed , Mrs. Ronayne . Should you return before midnight , it will be found with me ; if not , I shall at once carry it to Mrs. Headley . '' `` Just so . Good by , Nixon ! '' and as she placed the packet in his possession , she pressed his hand , as if to signify that the proper execution of the commission was of some importance .