When communication is lost with the Black Arrow rangers of the distant garrison at Fort Rannick, the mayor of Magnimar dispatches Ezren, Merisiel, Valeros, and Harsk to investigate. As a storm brews over Hook Mountain, the adventurers find the fort ransacked and the Black Arrows massacred. Were they betrayed by one of their own, or are the local ogre clans preparing for war? With rising floodwaters threatening to destroy the town of Turtleback Ferry, Ezren, Merisiel, Valeros and Harsk must face their destiny high up on Hook Mountain if they are to stand against the ancient evil returning to Varisia.