Titles and synopses are released for the first four episodes of the Doctor Who spin-off The War Between the Land and the Sea. The series, featuring a conflict between humans and an ancient ocean-dwelling race, stars Russell Tovey as Barclay Pierre-Dupont and Gugu Mbatha-Raw as Salt.

Episode 1: Homo Aqua — 7 December 8:30pm
An ordinary man finds himself caught in the conflict between land and sea as the Thames reveals some terrifying secrets.

Episode 2: Plastic Apocalypse — 7 December 9:15pm
Barclay becomes humanity’s ambassador when the mysterious Salt emerges from the Tank. But his family’s life is torn apart when Salt wreaks revenge upon all mankind.

Episode 3: The Deep — 14 December 8:30pm
Barclay makes a terrifying descent into the world of Homo Aqua. Back on the land, Kate stands alone as Downing Street conspires with the army to change the course of the war.

Episode 4: The Witch of the Waterfall — 14 December 9:20pm
Barclay and Salt go on the run in a war-torn London, as UNIT reels from disaster. But when Tide threatens the land and Gunsberg advances his plans, the Severance plans demand blood.

The title and synopsis for the fifth and final episode is not yet available. It will transmit on 21 December.

Lachelle Carl is credited for the first, second and fourth episodes. Might we see American newsreader Trinity Wells again?

Written by Russell T Davies and Pete McTighe and directed by Dylan Holmes Williams, The War Between the Land and the Sea will begin transmission on BBC iPlayer and BBC One in the UK on 7 December 2025. The spin-off series will transmit exclusively on Disney+ outside of the UK (where available) some time in 2026.