The jungle nation of Sargava is a colony on the verge of the vast jungle wildlands of the Mwangi Expanse, a place where numerous powerful factions clash for control. When rumors of a route to a mythical lost city surface, four factions (the Red Mantis assassins, the Pathfinder Society, the Aspis Consortium merchant league, and the Pirate Lords of the Shackles) engage in a race to be the first to claim this lost city's treasures - and the first step! A Pathfinder Roleplaying Game adventure for 1st-level characters, this volume of Pathfinder kicks off the highly anticipated Serpent's Skull Adventure Path, in which the heroes brave a trackless jungle to discover the legacy of lost empires. Supplemental articles contain rules for the four competing factions in the campaign, with tips on how the heroes can join forces with them or contest their goals, as well as an overview of the ancient serpentfolk of the Mwangi Expanse and their eerie magic. The Pathfinder Bestiary section introduces five all-new monsters perfect for Serpent's Skull adventuring.