In Ruathym, the Hall of Black Waves has been taken over by the Storm Maiden and her frost giant followers, bent on desecrating it and turning it from Valkur to Umberlee! Mouse returns home to the Moonshaes to help the firbolg tribes fighting humans there, but it causes a rift in the party when Lallagh, leader of the firbolgs, suggests destroying Rogarsheim and all the humans in it. Will Mouse lead his people to victory or protect the humans of the island? 

Includes material from Call from the Deep and other Forgotten Realms lore.