In a foggy town, a network of underground tunnels called "The Underwood" hides ancient secrets. Clara, a 14-year-old girl, searches for her missing brother, Tommy, believing the tunnels hold the key. Teaming up with Jaxon, a local outcast, they explore the tunnels, uncovering artifacts and facing mythical creatures. Clara learns the disturbances in town result from an imbalance between the human world and a magical realm. In the climax, she realizes her true strength lies in her connections, leading to a decision that will shape their future and family bonds.