A young man named John Hector McFarlane is falsely accused of murdering Jonas Oldacre. Despite his protestations of innocence, there's no evidence to be found in his defense. Until Holmes takes the case, of course. By using some forensic science and staging a fake fire, Holmes is able to flush Oldacre out of hiding. Oldacre tried to revenge himself upon McFarlane's parents by faking his death and framing McFarlane.