The gang races through the swamp only to stumble upon previously unexplored territory that leads them right into the middle of a mystery. As if the puzzling new discoveries aren't enough, Poetry's lamb causes mischief in the schoolhouse and gets everyone into hot water with Miss Lilly. When things calm down, the gang plans an overnight stay in a cave near the cemetery, but Tom Till has been keeping a secret that is sure to shake things up. Matters get even more interesting when Old Man Paddler appears and reveals the truth behind the gang's secret hideout.