Doctor Who: Time and the Rani

Assailed by violent bolts of energy, the TARDIS is blasted off-course and forced to land on the barren planet of Lakertya. The turbulence triggers the Doctor's sixth regeneration - but that is the least of his worries. Why has the Rani, that ruthless renegade Time Lady, brought the Doctor to Lakertya? What are the hideous Tetrap guards? Who are the 11 geniuses she has imprisoned in her stronghold, and what is the vital significance of Strange Matter? Aided by the faithful Mel, the Doctor must do all he can to stop the Rani's diabolical scheme before it affects the whole of creation