They move among us and prey upon us. Some are invisible. Some look like us. Some are inside us. Jimmy Temple was heading home on a gray and colorless evening when he died. The razor flew from an alley and sliced into him. It was a ripple, a blur, like a heat haze or the thinnest imaginable sheet of cellophane passing over the mouth of the alley. Then it was slicing through skin, muscle, and bone.