After losing the boat that had become their home, oldest Fitzgerald-Trout, Kim, has put finding a home back on her to-do list. When her sixth-grade history assignment offers a clue about the ruins of a volcanic house built by an explorer on Mount Muldoon, she and her siblings set out to find it. The castle they discover surpasses their wildest dreams. But having a permanent home offers more challenges than the Fitzgerald-Trouts expect, especially when they begin to suspect their home is haunted.