Owen Brown is just an average fourth grader trying to survive the school day. But his ordinary life is flipped entirely upside down when his best friend, Dana, suddenly vanishes. She does not just run away; she drops straight through the floor of their school right in front of his eyes. Determined to save her, Owen refuses to wait around for adults to notice she is gone. He teams up with his friends Jon and Sydney to launch a daring rescue mission beneath the school. They soon discover that a terrifying, secret world is lurking right under their feet. Dana's disappearance is not a simple accident. It is the beginning of a massive mythological riddle, and Owen, Jon, and Sydney are standing right at the center of it. Dive into this action-packed adventure to see if these brave friends can survive the underworld and bring Dana home safely.