Biggles and the team are given the task of checking far-flung islands for illegal bases setup by the pesky russians to disrupt air trade. And while this may be something like the proverbial needle in a haystack, the team do us proud and find just such a base within a few chapters.

The illegal russian base is on a French island several hours south of South Africa. When Biggles flies home to tell Raymound about it, the rest of the team managed to get marooned when the bad guys return in their submarine, first trapping Marcel and Ginger in a cave, and later trapping all of them when they mine the landing bay.

Biggles returns in time to save them all, and to watch the bad guys blown up by their own mine.