midnight
`` My plan was a simple one , and it was odd that I had not thought of it before ; but after all , it would have been impracticable as long as my wife and sister-in-law were in the house . `` On Tuesday night I sprinkled a thin layer of flour over each stair , from basement to attic . This was a task of an hour or so , but I felt that I did not labor in vain . Then I turned in and slept soundly until midnight , when I was awakened as usual by the creaking of the stairs . It is hardly necessary to say that I remained in bed , making no attempt whatever to investigate , but valiantly drew up the covers over my head , fully expecting every moment to feel the weight of a dreadful hand upon some portion of my body . `` In the morning , my bravery having returned , I found upon each stair the clear impression of a naked human foot ! The footprints were very large , and were made in ascent .