"Dusty Ermine" refers to the dustiness of the legal ermine worn by the Kent family, who have been judges and lawyers since the days of James II. Their honourable record is marred by Uncle Jim, a very amiable, lovable old gentleman, who comes back after doing a five-years "stretch" for forging bank-notes. A second blow for Walter Kent, K.C., is the fact that his penniless son Gilbert, who has taken silk, has taken a wife almost at the same time, and plants himsdelf and his wife and baby on to the paternal household. It transpires that young Gilbert is as expert a forger of banknotes as his uncle and detectives are set to watch the house, the inference being that Uncle Jim has been up to his tricks again. Such, however, is not the case. Eventually Uncle Jim gets himself arrested in Gilbert's place for the sake of his young wife and baby, and goes off to do another stretch. This act of noble sacrifice, however, does not cure Gilbert, who goes on forging just the same. The result is that Uncle Jim is released before his time, and the detectives get on to the real track. A confederate squeals and Gilbert comes to a nasty finish.