Sherlock Holmes and the Blue Diamond

It is December 26, 1889. The Countess of Morcar reported the "Blue Carbuncle" - a rare blue diamond - as stolen five days earlier at the Cosmopolitan Hotel. The 26-year-old plumber John Horner is handed over as the suspected thief, who has already been convicted of a similar offense and was in the hotel at the time of the crime. Help Sherlock Holmes bring the truth to light and find out as a team: was it actually the plumber who stole the diamond? Can you recover the priceless gem? And remember: you only have 60 minutes!