In Equatorial Encounter, Joseph Nelson was a secret agent working for the British government in equatorial West Africa.
For some time, British industry had come to rely upon shipments of valuable botanical oils and gums from plantations operated by a Scottish planter named Anderson in the interior of Sierra Leone in equatorial West Africa. When the shipments began to dwindle and then dry up and contact with Anderson was lost, the British government sent Nelson, a Jamaican, to investigate. Nelson was unable to locate Anderson, but reported that work at the plantations appeared to be going on normally. Later, he reported that there were rumours that aircraft were operating to and from the hinterland, using a new airstrip. Thereafter, contact with Nelson was lost. It was assumed that Nelson had run into trouble while attempting to confirm the existence of the airstrip.
Biggles and co. were sent in after Nelson. After a thorough air search, they located a secret, camouflaged airstrip which had been built by an American gangster Griggs. Griggs had taken Anderson prisoner, locking him up in a hut at the airstrip and denying him of quinine, waiting for him to die of fever. Griggs and his fellow gang members had then enslaved Anderson's plantation workers using an African witch doctor, forcing them to continue work at the plantation and shipping the products out to Boufle by air and then by rail to Port Bouet, both in the French Ivory Coast. Nelson had stumbled upon this operation and had also been captured, beaten and then locked up with Anderson.
As the airstrip lay just inside French territory, Biggles summoned Marcel's help. Together they flew into the airstrip to apprehend the gang. The gang resisted arrest and a brief shootout ensued, leaving Griggs dead and a French policeman injured. The remaining members of the gang escaped in their aircraft but were arrested later on their arrival at Boufle. Anderson and Nelson was freed. Nelson was flown to a hospital in Freetown, Sierra Leone, while Anderson elected to remain behind to continue work on his plantations.