When Tintin and Snowy travel to Syldavia with Professor Alembick, they find themselves mixed up in a plot to depose King Muscar XII. He will be overthrown if he does not have King Ottokar's Sceptre on the day of the Royal Procession. When rebels steal the sceptre, Tintin and Snowy follow Thomson and Thompson as they seek to retrieve the sceptre before it is too late.