Boy Underground by Isabelle Marinov

For Hugo, the world can be too loud and bright. He likes the quiet. He likes the dark. And he loves maps.

When Hugo learns that there’s a whole other world under Paris, a network of tunnels, quarries and catacombs mapped beneath his feet, he sets off on an adventure.

Navigating secret passages, narrowly escaping robbers and returning to old friends, Hugo discovers more than just buried treasure …