On board the 500-ton super-luxury diesel-engined yacht Cordelia was thought to be Otto Brandt, international financier and one time multi-millionaire. Why did he pull out of England in such a strange and intriguing way? And why was his yacht loaded with ammunition? Biggles, Algy and Ginger fly across the world to discover his store depot on an island in the Bahamas and the reason for the disappearance of this Mystery Man of Europe.