Ironfang Invasion Adventure Path. Starting with book 1 of 6, 'Trail of the Hunted'.

War Comes Unbidden The Ironfang Invasion Adventure Path launches with "Trail of the Hunted," a tale of desperate survival set against the invasion of a ruthless hobgoblin army—the Ironfang Legion! As the Ironfang Legion begins carving out an empire of monsters, the heroes must flee their hometown of Phaendar as it burns, saving any lives they can. The heroes guard their band of survivors in the wilderness, challenge a troglodyte tribe for safe haven, and face the brutal bounty hunters dispatched to end their flight to freedom!