Arriving on the almost impossibly ancient planet of Hyspero, a world where magic and danger walk hand in hand, the Doctor and Sam are caught up in a bizarre struggle for survival. Hyspero has been ruled for thousands of years by the Scarlet Empresses, creatures of dangerous powers — powers that a member of the Doctor’s own race is keen to possess herself: the eccentric time traveller and philanderer known only as Iris Wildthyme.