In Biggles Works Overtime, Janapoulos was the name of a Greek pearl dealer who lived in the town of Suakin on the Sudan Red Sea coast. When Biggles learnt that Sheikh Ibn Usfa of El Bishra had been murdered and pearl collection stolen, his suspicions fell on Eustace Bowden who had gone missing after the plane he was supposed to be flying crashed. Biggles reasoned that Bowden might have attempted to sell the pearls to Janapoulos, since he was the Sheikh's regular pearl dealer and lived at Suakin which was nearby, across the Red Sea from El Bishra.
Accordingly, Biggles called at Janapoulos' residence at Villa Verde on the Stretta Gonzales in Suakin. Janapoulos was alarmed to hear of the Sheikh's murder. He confirmed that Bowden had offered the pearls to him but he did not buy the lot because they were far to fine and expensive for him. Also, he told Biggles, he was suspicious of Bowden because he would not tell him how he came to be in possession of the pearls. He only a small pearl because Bowden was in urgent need of money and paid him five hundred pounds in a mixture of Egyptian pounds, some dollars but mostly in French francs. Janapoulos thought Bowden wanted francs because he planned to board a French boat, the Charbonniere which was due to call at Suakin, bound for Marseilles. Janapoulos later watched Bowden and confirmed that he had boarded the boat.
Janapoulos was also able to tell Biggles where Bowden was probably headed: Paris. He had given Bowden a note of introduction to Cortons et cie, in the Rue de la Paix, where he usually sent customers who had pearls which were too expensive for the local markets.
No doubt Janapoulos was motivated to keep out of trouble by cooperating with the police but his information proved instrumental in Bowden's eventual downfall.