In The Lady From Brazil, Dolores Cantani was cabaret dancer in a well-known night club in Rio de Janeiro whom Biggles caught smuggling emeralds in a rather novel fashion.
Cantani was a friend of Jose da Silvaro who derived a substantial income from emerald mines in the interior of Brazil. Da Silvaro had a brother in London who managed the European side of his business. Foster, an official with H.M. Customs became suspicious when he learnt that Cantani had visited London, spending several months pay in airfare for a short visit of only a week. During her visit she had declared and paid duty on a small quantity of inferior emeralds intended as presents. Cantani made two more visits to London over the next few months, each time declaring and paying duty on poor quality gems. Foster became convinced that she was smuggling in something more valuable which she was not declaring, but detailed searches yielded nothing.
Foster approached Air Commodore Raymond for help and Biggles was sent to Rio de Janeiro to shadow Cantani when it was learnt that she was planning another visit. Biggles boarded an Inter-Atlan Airways aircraft with Cantani at Rio. Beyond the fact that she always asked for seat number 7, there was nothing unusual about her behaviour the entire flight.
After arrival, Cantani passed through customs without them finding anything and Foster was beginning to think that they had failed again. However Biggles noticed a girl, Miss Varros among the maintenance crew who boarded the aircraft after arrival. She was chewing gum, just like Cantani had been during the flight. Suspecting a link, Biggles and Forster approached Varros and asked to see the gum she was chewing. Frightened, Varros produced the gum which was found to contained two valuable emeralds. Varros made a full confession, saying that she had been persuaded to help the smuggling racket by Cantani. who was her half sister, and da Silvaro, for whom she used to work. Varros' part in the racket was to retrieve the jewels which Cantani stuck under seat number 7 with chewing gum.