This book is pretty unique in that it does not actually involve an aircraft. Instead Biggles and Ginger travel to a small village in Mexico to try and retrieve some stolen diamonds.

The diamonds have been stolen by a group of misfits who, after missing one appointment with a buyer, end up running to the US, and then to Mexico, to await another deal. It ends up with the diamonds hidden in a car that Ginger manages to borrow and lose in the desert. At that point (finally) an aeroplane comes into the picture in helping find the car.

Biggle's visit to Von Stalhein is notable, particularly for how the relationship between these two arched enemies is deemed to have continued. Von Stalhein is described as making a living doing translation work, and going under the name of Lothar Boelke.