Police Inspector Gaskin was bothered him terribly that he couldn't get a grip on the perpetrators of a series of brutal jewelry thefts. The gang that planned these crimes was so sophisticated that the police didn't stand a chance, because no trace was left behind. Finally, however, although he could not prove it, the inspector became convinced that the gang was operating on a plane. And that made him decide to enlist Major Bigglesworth, in order to fight the unknown and invisible enemy, as it were, with his own weapons. Of course that was right up the alley of Biggles and his men. Biggles, with his vast experience fighting the underworld, thought he could afford a stunt... by offering his services as a pilot for the gang. He was quickly accepted into his job as a jewel thief. But it was only when it was too late that he discovered that he had completely underestimated the leader of the gang and that his hubris had made him no longer the hunter, but 'the hare'.