In Biggles and the Blue Moon, Lin Seng was a wealthy Chinese merchant who called on the British government for help when he found himself besieged by bandits in his countryside villa. According to Air Commodore Raymond, Lin Seng had the reputation of being one of the wealthiest people in the world and had built up a magnificent collection of pearls which included a priceless rare specimen known as "The Blue Moon of Asia".
Lin Seng lived in a villa built by his father at Taihan in the northeast of peninsula Malaysia. Although palatial in scale, it was surrounded by jungle, with twenty mile long access road being the only link to the the outside world. Both the location of his villa and his collection of pearls were to conspire to be a major source of grief. His only children, a daughter and a son had both been murdered by criminals intent on gaining access to his pearls and later Lin Seng found that bandits had sealed off the access road making it dangerous to travel out of Taihan, and forcing him to live with armed guards, electric alarms and dog patrols--a lifestyle more akin to a prisoner than a millionaire.
Faced with this predicament, Lin Seng appealed to the British government for help. The British government agreed, primarily out of a debt of honour because Lin Seng had served the British well during the Second World War, using his vast commercial interests to run a network of spies to supply the allies with valuable intelligence about Southeast Asia.
Biggles was detailed to the case, and travelled to Malaysia with Algy on what would turn out to be a standard "extraction" mission which succeeded in transporting Lin Seng and his precious pearl collection out of Taihan, first to Kuala Lumpur and then to London. Besides the bandits, Biggles and Algy also had to cope with Indonesian commandoes infiltrating into Malaysia (the book was set against the backdrop of the Malaysian-Indonesian Confrontation). Usually in these tropical jungle settings, Johns would also throw in the monsoon weather and a wild animal or two but not this time.