A long, restless night has finally dawned into a clear, sunlit day, perfect for the coming test of Simon Gore's jet propelled flying wing. Hop has persuaded Major McColl to allow him to fly the experimental plane, although he is hiding the fact that he has been injured in the crash of their Piper the night before. Right now, Hop and Tank are on their way to the Major's office, walking slowly through the long winding tunnels...