The Power of Nothing
Steve Granger is sure there is something wrong with the grey man, and when he starts to follow him, Steve knows he's right. When Steve can't get rid of the grey man, he erupts and kills him. The next morning, as Steve is leaving his home to get rid of his blood-splattered clothes, he finds the grey man standing on his doorstep. Steve learns that killing the man a second time is easier, but the man keeps coming back.