For many months, the BBC has kept tight-lipped about the upcoming 13th season of its cult sci-fi series Doctor Who. Aside from a few cast announcements and a teaser trailer for San Diego Comic-Con, the corporation has kept its cards close to its chest, with fans speculating on everything from returning monsters to when the first episode will air.

Now that we have definite details on the Doctor's return, here's a comprehensive guide to everything we know.

RELATED: Doctor Who: The Edge of Reality Sees David Tennant Reprise His Role

Is This the Final Season for Jodie Whittaker's 13th Doctor?

Thirteenth Doctor smiling in Doctor Who

It was confirmed in July that Jodie Whittaker will leave Doctor Who along with showrunner Chris Chibnall next year. Therefore, Season 13 will be the last full season starring Whittaker as the 13th incarnation of the Doctor. She will then appear in three specials, the first two airing on New Year's Day and in Spring 2022, respectively. On Oct. 13, Whittaker completed filming on the final special alongside Mandip Gill, whose character Yasmin Khan has been a companion to the 13th Doctor since her first episode in 2018. This special, presumably concluding with the Doctor's regeneration, will air in Fall 2022 as part of the celebrations commemorating the centenary of the BBC.

Russell T Davies will then return as showrunner in 2023, replacing the outgoing Chibnall. Davies, who relaunched Doctor Who to great success in 2005, will cast Whittaker's successor as the Doctor, guiding the show through its 60th anniversary and beyond. Chibnall will reunite with former Doctor Who Executive Producer Julie Gardner and former BBC Head of Fiction Jane Tranter, whose company Bad Wolf Productions will co-produce the program.

RELATED: Russell T Davies Is Doctor Who’s Last Hope - to Save the BBC

Does Doctor Who Season 13 Have a Trailer?

There are two teaser trailers for Season 13, the first debuting during Comic-Con@Home 2021 and the second released on Oct. 9. The former provided the first glimpses of John Bishop as new companion Dan Lewis and Jacob Anderson as recurring character Vinder. The latter is a video message from the Doctor, who warns of a host of alien invaders that will arrive with the mysterious "Flux."

A full-length trailer (above) was unveiled on Oct. 15 during The Graham Norton Show before being released online. It showcased the various monsters the Doctor mentioned in the second teaser, including returning villains such as the Sontarans and Weeping Angels. It also confirmed the surprise reappearances of the Ood and the Cybermen, specifically the Cyber-Warrior versions from Season 12's "Ascension of the Cybermen."

RELATED: Doctor Who's Billie Piper Really Wants to Return to the Series

What's Known About the Story of Doctor Who Season 13?

Season 13 consists of a six-part story called Flux, with the first episode being titled "Chapter One: The Halloween Apocalypse." A clip from the episode (above) introduces Dan Lewis, who will likely join the Doctor and Yaz after Sontarans appear in his home city of Liverpool, where the BBC ran a promotional campaign to promote the new season. This included projecting an image of a Sontaran spaceship into the night sky, which was highlighted by the official Doctor Who Twitter page. The second episode, "Chapter Two: War of the Sontarans," pits the clone soldiers against the British Army during the Crimean War, where the new TARDIS trio will undoubtedly find themselves. If the full-length trailer is to be believed, this will be one of many locations and time periods visited in this massive adventure.

This serialized format is a huge departure for Doctor Who, as previous seasons usually spread a loose arc across mostly standalone episodes. Chris Chibnall has confirmed that he wrote all six episodes, collaborating on the fourth with Maxine Alderton, who penned Season 12's Mary Shelley story, "The Haunting of Villa Diodati." Also returning from Season 12 is director Jamie Magnus Stone, who has helmed episodes one, two and four, while the rest have been directed by newcomer Azhur Saleem.

When Does Doctor Who Season 13 Premiere?

Doctor-Who-Flux-Poster

Doctor Who: Flux will premiere at 2.25 pm ET on Oct. 31 on BBC America in the United States, the same time it airs at 6.25 pm GMT on BBC One and BBC iPlayer in the United Kingdom.

This article will be updated should further information become available prior to broadcast.

KEEP READING: Doctor Who's First Russell T Davies Era Almost Ended Very Differently