Biggles is intrigued by a mystery. Supply ships have been disappearing in the Indian Ocean and before they sank they managed to broadcast a final message. In all cases, when they referred to the word "weather" it was misspelt as "whether". Biggles concludes that the same person sent the messages otherwise the coincidence would be too great. Biggles approaches Colonel Raymond, now with Scotland Yard, but formerly with the Air Intelligence staff when Biggles was in 266 squadron, to find out more information. Before he knows it, Biggles is dining in the Foreign Office and setting out his ideas about how to deal with the problem. Biggles is given a temporary commission in the Royal Air Force with the rank of Air Commodore and his plans are put into effect.