Holmes is consulted by Mason, head trainer at the racing stables owned by Sir Robert Norberton and his sister Lady Beatrice Falder. Mason is very concerned about his employer's behaviour towards his sister. He has taken her pet spaniel away from her and has taken to visiting a ruined crypt of a night time. Human bones have also been found in the furnace at Shoscombe and Mason is worried about changes in Lady Beatrice's behaviour. Mason suspects that the brother and sister have had a major falling out.
Holmes and Watson visit Shoscombe under the guise of anglers and discover that Lady Beatrice's spaniel Jasper has been given to the owner of the local inn. Holmes takes Jasper for a walk and when Lady Beatrice appears in her carriage he releases the dog who is at first enthusiastic to see his beloved mistress, but then retreats in confusion.
Ultimately Holmes solves the case - and justice is again tempered with mercy.