What is the main setting in the novel, Doctor Who - the Art of Destruction?

The bulk of this story takes place underground. This adds mystery and danger, keeping the story suspenseful. The characters run from enemies and aliens, finding themselves in dead-ends and narrow passageways. The temperature is very hot outdoors, and cooler in the caves. There are rock formations and caves the characters use to evade enemies and to further their research. The underground setting adds a sense of intrigue because the world outside knows nothing of what is happening down under the ground.