The Flux is Coming... (TV story)

The Flux is Coming... was an advert 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 being welcomed aboard the TARDIS in the full-length television episode War of the Sontarans. 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. Cinematic showings were also featured in cinemas leading up to Flux, though the Doctor was inexplicably alone in those teasers.

Publisher's summary
Be ready...

Plot
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".

Cast

 * Thirteenth Doctor - Jodie Whittaker (uncredited)
 * Yasmin Khan - Mandip Gill (uncredited)
 * Dan Lewis - John Bishop (uncredited)

Worldbuilding

 * The distress call comes from within the Doctor's TARDIS.

Continuity

 * The Doctor mentions several enemies who appeared in TV: The Halloween Apocalypse and onwards.