The Zygon Inversion (in-universe)

The Zygon Inversion was the eighth episode of the ninth series of Doctor Who. It followed The Zygon Invasion and was succeeded by Sleep No More.

It featured the Doctor, Clara, Osgood, as well as an individual resembling Kate Stewart. Its synopsis mentioned that "with UNIT neutralised, only the Doctor [stood] in the way" of the Zygon threat. By 10 May 2020, the episode was available on the BBC iPlayer along with the rest of series 9. (WC: The Zygon Isolation)