chunk: By studying Cecil Barker's slippers, Holmes determines Barker's shoe made the mark on the window, to give the appearance that someone exited that way. In their lodgings, Holmes tells Watson that Cecil Barker and Mrs. Douglas are certainly lying: when a shotgun is fired at close range, the sound is muffled. Moreover, Holmes learns that the housekeeper heard a door slamming half an hour before the alarm, which Holmes believes was actually the murdering shot. White Mason, the Sussex detective, and MacDonald track a bicycle found on the grounds of the house to an American staying at a guest house. The American appears to be the murderer, but there is no sign of the man.