Sierra settles into life in Bresslewood, but they are soon hit with another disaster that would involve all eight realms and the creation of a new realm. The race of Invisibles is tricked and use Dak and Mavis in their ill-fated scheme that backfires and releases an evil that threatens the realms. Out of the darkness and despair also come beautiful friendships that work together to fight the disease that threatens them. As they fight for the eight realms, ancient trouble is brewing back home. The banished elders have discovered a way back to the eight realms. Their return forces Egon to enlist the aid of Sierra to drain the magic left behind after the elders war. Egon's son, Ben, is among the returned. Ben struggles with his desire for revenge against his father and his longing to start over.