Read it through once

I walked back along the border of the lawn, traversed the gravel softly, and tiptoed up the veranda steps. The drawing-room curtains were open, and I saw that the room was empty. Crossing the porch where we had dined that June night three months before, I came to a small rectangle of light which I guessed was the pantry window. The blind was drawn, but I found a rift at the sill.