When she awakened it was rather suddenly, and she did not know that any particular thing had called her out of her sleep. The truth was, however, that it was a sound which had called her back--a real sound--the click of the skylight as it fell in closing after a lithe white figure which slipped through it and crouched down close by upon the slates of the roof--just near enough to see what happened in the attic, but not near enough to be seen.