Three aircraft with VIP's aboard are missing in Africa. Biggles and the team are called in. They find themselves facing Erich von Stalhein and another nefarious scheme.

goodreads summary

Biggles is sent to investigate the disappearance of aircraft over Africa. The aircraft contained V.I.P.'s who were carrying with them secret documents. Pretending to carry a V.I.P. in his aircraft, Biggles is forced to land in Liberia after a secret weapon causes his plane to suffer engine failure. The picture on the dust cover of the book is Biggles' plane coming down. Ginger is in Biggles' plane and he escapes into the jungle whilst Biggles is captured and taken to meet Christophe, a black American who is planning to set up a black empire in Africa. He has stolen a new American plane containing the secret weapon and is using it to steal secrets to sell to the highest bidder, in order to finance his scheme. Biggles is put in a prison compound with other prisoners taken from planes captured earlier. Biggles discovers that behind Christophe are Iron Curtain agents, including Von Stalhein and Zorotov (from Biggles in the Blue). Meanwhile Ginger has made contact with Algy and Bertie and Algy has flown back to base to get a smaller aircraft as there are difficulties landing in the rough terrain. Von Stalhein offers the captured Biggles wire-cutters to escape in a deal that would see him double crossing both Christophe and Zorotov, whom Von Stalhein later shoots. Ginger and Bertie however, have found where Biggles is and get the wirecutters off Von Stalhein. With these, all the prisoners escape and steal a plane to get away. Biggles, Ginger and Bertie remain to destroy the aircraft with the secret weapon. Biggles sabotages Christophe's radio and leaves him without communications. Von Stalhein flies off to an unknown destination but returns with a small army and attacks Christophe and his men. Biggles uses a petrol and oil dump to destroy the secret weapon. With this gone, there is no reason for Von Stalhein to remain. An exhausted Biggles and Ginger, together with an injured Bertie fly to safety when Algy returns and they take with them Christophe who they find has only been wounded in the attack.