The PCs are now the masters of the lost city of Saventh-Yhi or are they? For no sooner is the city won than the mighty Gorilla King and his simian followers come to take it for their own. At the same time, the PCs learn of a missing Pathfinder imprisoned in a subterranean city beneath their new holding. Before they can rescue him, however, the PCs must venture into seven ancient vaults to find the entrance to the hidden city. Can they survive the dangers of these strange constructions, or will they succumb to madness first?This volume of Pathfinder Adventure Path includes: "Vaults of Madness," a Pathfinder RPG adventure for 10th-level characters, by Greg A. Vaughan. A dozen deadly new traps, by Gareth Hanrahan. An ecology of the terrifying ape-men known as the charau-ka, by Gareth Hanrahan. Demon birds and enraged apes in the Pathfinder's Journal, by Robin D. Laws. Five new monsters of the jungle, by Jesse Benner and Jason Nelson.