The Flux is Coming... was a prelude to Doctor Who: Flux, teasing the titular catastrophe through an in-universe distress call from the Thirteenth Doctor. The short television minisode, similar to the Christmas idents, came first in short "stings", then was broadcast in full on BBC One on 9 October 2021, preceding Strictly Come Dancing.
This short video became the first appearance of Dan Lewis as a companion, taking place after, but airing before, his coming aboard the TARDIS in the full-length television episode The Halloween Apocalypse. John Bishop's as-yet-unnamed character had earlier been revealed in an especially-shot minisode, Welcome to the TARDIS..., which aired after the credits of Revolution of the Daleks, taking place prior to his meeting the Thirteenth Doctor.
Initial iterations of The Flux is Coming... were presented as "glitches", coming in and out of view during regular BBC One programming.
The Thirteenth Doctor sends a distorted distress call while Yaz and Dan studiously pilot the TARDIS at the console. The Doctor warns of the impeding arrival of the Flux as well as Sontarans, Weeping Angels, the Ravagers, and other creatures from across the universe. Dan calls to the Doctor, telling her that they need her help, so the Doctor concludes by saying "be ready".
- Thirteenth Doctor - Jodie Whittaker (uncredited)
- Yasmin Khan - Mandip Gill (uncredited)
- Dan Lewis - John Bishop (uncredited)
- In the subtitles of the story released on the BBC America YouTube channel, the Ravagers were called "the Ravages".