Released in the US as Starship.
In a strange world of huge overgrown corridors, Roy Complain and his tribe eke out an existence by migrating slowly up the corridors, hunting for what they can, and breaking into the chambers on the sides in the hope of finding something useful. Encounters with outsiders are usually violent. Where they are and how they got there is a mystery lost in time.
Caution is the philosophy of the green tribe, but Roy is encouraged by Marapper the priest to join an unsanctioned expedition. As they journey further from home, Marapper explains his theory about the world they live in. A theory so strange it is barely conceivable to the others. But the truth of it becomes more and more undeniable with every encounter. Until they find themselves at the center of events that will change their very existence forever.
This book sits firmly in my “why haven’t they made a movie” file. The reader is drawn into this harsh and eerie world and is swept along by the story.