Biggles and the team discover why a series of diplomatic flights have mysteriously disappeared over Central Africa. In doing so they uncover a Liberian dictator seeking to build up a private army by using a stolen secret weapon (that cuts airplane engines and forces them to land) to obtain secrets and sell them to the Russians.

The stolen weapon, installed in a special aircraft, had been stolen with the help of the Russians and eventually they borrow a few commandos to try and take it back. Unfortunately that is not before Biggles has managed to rescue all the passengers from the downed planes and set fire to the aircraft, preventing its theft.