Tintin and his dog Snowy visit their friends Captain Haddock and Professor Calculus at Marlinspike Hall. There, they learn that Bianca Castafiore, her maid Irma, pianist Igor Wagner and the detectives Thomson and Thompson have been imprisoned in San Theodoros for allegedly attempting to overthrow the military government of General Tapioca. Tapioca’s government have further alleged that the plot was masterminded by Tintin, Haddock, and Calculus themselves. Tapioca invites the trio to visit San Theodores, promising them safe passage, but Tintin deems it to be a trap, leaving Haddock and Calculus to go alone. Once there, the Captain and Professor are taken to a rural villa, where they are closely monitored by the security services.