When their homes in Astoria, Oregon, face demolition, Mikey Walsh and his friends discover an old map leading to the legendary treasure of the pirate One-Eyed Willy. Hoping to find enough riches to save their neighborhood, the group follows the map into a network of underground tunnels filled with traps and hidden dangers. Their adventure becomes even more perilous when the criminal Fratelli family begins pursuing them, determined to claim the treasure for themselves.