All 21 titles also available as audiobooks!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... Fantastic new cover art by Laura Ellen Anderson will draw young readers into this accessible timeless classic.