- "I want you to start an airline"
- is the request from Raymond (now Assistant Commissioner of Police at Scotland Yard). So Biggles starts an airline to transfer gold shipments, to stop a series of thefts. Using his natural cunning, Biggles manages to thwart the bad guys a few times, before the ringleader (the old friend Von Stalhein) ups the ante by kidnapping Algy and locking him in a castle in Germany. Biggles and Ginger come to the rescue, eventually, returning the team and its goods to London.
- On their return the final piece of the puzzle falls into place, when one of Biggles employers is exposed as a double-agent, giving Von Stalhein's men the tip-offs needed to capture the gold and precious stones... but there is yet another twist...