Perhaps because of his father's influence, Will is a boy whose hobby is digging tunnels.
One day, he discovers a tunnel that his father, who had suddenly disappeared, had secretly dug.
In addition, from his father's notes left behind, he learned about the existence of suspicious pale men and the unknown history of the city.
With his best friend Chester, Will tries to find the key to his father's disappearance by digging up a deliberately blocked tunnel.

Will his father ever be found?

What they find at the end of the tunnel is a secret that could cost them their lives.