Time and the Rani

He glared bleakly at the Rani. "That asteroid's composed of strange matter! What monstrous experiment are you dabbling in now?"

Assailed by violent bouts of energy the TARDIS is blasted off course and forced to land on the barrent planet of Lakertya, and the violent buffeting triggers the Doctor's sixth regeneration. But that is the least of his worries. He has been hijacked by that ruthless renegade female Time Lord, the Rani.

Why has the Rani brought the Doctor to Lakertya? What are the hideous Tetrap guards? Who are the eleven geniuses she has imprisoned in her stronghold? What is the vital significance of the asteroid of Strange Matter? And can the Doctor stop the Rani's diabolical scheme before it affects the whole of creation throughout time and space?