A dark and silent planet. 

A magnificent crystal edifice, perched on a mountainside. 

A legion of dormant robots, waiting for the signal to bring them back to life. 

The Doctor and his granddaughter Susan, and their reluctant companions, Ian and Barbara, are about to unleash forces which will threaten their very survival. 

Read for the first time the complete script of this magnificent, but regrettably never produced, Doctor Who story.