Doctor Who - Season 18 Episode 17 -

Nowhere, literally - the Zero Point between the positive and negative universes. The TARDIS materialises in a white void, but the travellers are not alone. A stone gateway, filled with ageing warrior robots and a very strange hall of mirrors, is also in the void. As is a slaver ship filled with the time-riding Tharils, and captained by the increasingly unstable Rorvik...