PCs attempt to infiltrate Riverguard Keep, but are betrayed by the boatmen they leave on the boat. A great battle ensues. Dozens of cultist Reavers swarm from all directions, backed by Dark Tide Knights, Priests, and a strange snake made of water that envelops Ralf and tries to drain his life energy. The master of the keep, Jolliver Grimjaw, turns out to be a wereboar and immune to mundane weapons & Rhenya's insect swarm - but not to the steel of Ralf & Kasumi. Eventually the keep is taken, and captives liberated. A secret tunnel leads down to a hidden boat landing.
The party plan to retreat to Red Larch for a long rest.