A blue carbuncle, a valuable jewel, is stolen from Lady Morcar, and an innocent workman charged and remanded in the run-up to Christmas. Holmes gets a visitor, a gentleman who belongs to a Christmas Club putting money by to purchase a goose for his Christmas dinner. Someone has tried to steal his goose. Another member of the club finds the carbuncle in the goose he has bought. Who put it there? Holmes must find out if one family is to avoid a miserable Yuletide.