In Biggles in the Blue, Napoleon Morgan is a Trinidadian operative in the employ of Erich von Stalhein and Boris Zorotov.
Biggles and Ginger first encountered Morgan in von Stalhein and Zorotov's hotel. Morgan was calling on Zorotov there. he became the subject of another of John's detailed word pictures. Morgan was dressed in a fantastically garish outfit. He wore beautifully pressed lilac trousers "tapered almost to a point at the ankles". He wore a square-shouldered, wasp-waisted jacket with long lapels which ended in a single large button. He had a broad brimmed hat snapped down in front to cover his face and a red tie decorated with dice and a large gold pin. Ginger thought the outfit would have looked ridiculous if it were not for Morgan's figure: he was tall and slim and "walked with the grace of a panther".
A waiter at the hotel told Biggles and Ginger that Morgan was a member of the local Communist Party. He had a nickname of "Nappy Morgan" and was always stirring up trouble. He was originally from Trinidad, where he had been a member of a gang called "the Saga boys". Morgan lived in a slum area near the railway yard of Kingston known as "the Dunghill".
Shortly about Commander Evans had been bitten by a snake at Rumkeg Haven, the house of ex-Nazi Werner Wolff, Biggles and Ginger spotted Morgan on a road nearby. Biggles remembered a warning from von Stalhein about snakes in the house and also connected the fact that Trinidad, where Morgan hailed from, has many venomous snakes. Biggles surmised that Morgan might have planted a snake there at von Stalhein's behest.
Later, when von Stalhein and Zorotov moved their search operations for Wolff's secret papers to the island of Inagua, Morgan was brought along and used on various reconnaissance missions. On one of these, Morgan encountered Ginger. Both of them were surprised by this chance meeting. Morgan moved to attack Ginger with a razor knife but Ginger shot him in the arm.
Towards the end of the book, Morgan was on the prowl again and discovered Ginger, who had been left to guard Wolff's box of secret papers. Morgan attacked Ginger, this time with a gun. In the ensuing battle, Ginger's gun jammed. Morgan charged at Ginger and would have killed him. Fortunately, Bertie, who was on the way to meet Ginger, arrived just in time and shot Morgan.
After Biggles had successfully wrapped up his mission, a Royal Navy frigate sent a shore party to Inagua to clean up. The wreck of the yacht used by von Stalhein and Zorotov was found, but they had already left the island. Morgan's body was never found.