Ribblestrop Forever!. by Andy Mulligan

The children are back! - but a air-crash and an unsteerable raft quickly land them in deep waters. Rescued by a mad librarian, they're soon off on a dangerous quest across the wilds of Ribblemoor, exploring haunted flare-paths. Can they uncover the ancient mysteries of a secret tribe? Can they survive the dangers of Lightning Tor? Inspector Cuthbertson is right behind them, determined to destroy the school for good: it'sthe final conflict...