A precious stone, the blue carbuncle owned by Countess of Morcar, was stolen in Hotel Cosmopolitan. John Horner was arrested and jailed for the crime based on the testimonies of James Ryder and Catherine Cusack, but the gem was not found. But with some bizarre events the gem landed on the hands of Sherlock Holmes, and with the help of a goose he found out the real culprits were James Ryder and Catherine Cusack.