Camping again, this time on Billycock Hill, near the farm of Toby, a boy from Julian and Dick's school. Toby was very proud of Jeff, his cousin and thought he was a hero. When Jeff, a British Air Force pilot, flies off late in a stormy night with the newest aeroplane which is full of secrets, the Five are stunned. The media claims Jeff has flown away and people think he is a traitor. Could Jeff really be a spy? But the Five and Toby don't think so because jeff was always an ordinary British air force guy.