In book sixteen, it's holiday time at Billycock Hill and the Famous Five make new friend - a real pilot! But when he disappears with top secret equipment, the Five begin to wonder if their new friend could be a spy, or worse, a traitor.
Whatever his motives, the gang feel duty-bound to investigate...
- Publisher: Hodder Children's Books.
- Publishing Date: 1957.
- Pages: 244.
