Read it through once

Dim and wavering as was the wind-blown light, yet it served to show him the hideous error, as it seemed, into which he had fallen, for the face of the man he had sought to kill had all the bloom of boyhood, all the unstained purity of youth. He seemed little more than a lad of twenty summers, hardly older, if older indeed at all, than his sister had been when they had parted so many years ago. It was obvious that this was not the man who had destroyed her life.