Set the scene for the Serpent's Skull Adventure Path or paint a vivid backdrop for thousands of untold wilderness adventures with this wide-ranging jungle campaigning sourcebook. Learn the terrible secrets that lurk below the darkened canopy of the Screaming Jungle, dare the treacherous territory of the Gorilla King, and explore the fallen air-cities of long-dead cultures! Discover the secrets to surviving in the hostile Mwangi Jungle -- and how to make it a memorable threat for players. Unearth lore about the strange creatures who live in the Mwangi expanse and their even stranger deities. All this and more awaits in this overview of the Mwangi Expanse, an unmapped green hell in the southern reaches of the Pathfinder Chronicles Campaign Setting.