The TARDIS lands on Nooma, a world in the midst of an industrial revolution. But the Doctor, Jo and Mike Yates quickly discover more: The sky is at war with the ground, with continents moving and somewhere, a starship has a role to play. Mike finds himself in a life or death fight, Jo is caught in a laborers' rebellion, and the Doctor must uncover what is happening to Nooma before the struggle for survival destroys all...
This storyline is a technical prequel to the Sixth Doctor story "Timelash", as the Doctor is intending to take Jo and Mike to the planet Karfel although he never reaches it in this novel; "Timelash" made it clear that the Third Doctor had visited Karfel at some unrecorded point with Jo Grant and an unidentified second companion.